libp2p DoS vulnerability from lack of resource management
Impact
Versions older than v0.18.0 of go-libp2p are vulnerable to targeted resource exhaustion attacks. These attacks target libp2p’s connection, stream, peer, and memory management. An attacker can cause the allocation of large amounts of memory, ultimately leading to the process getting killed by the host’s operating system. While a connection manager tasked with keeping the number of connections within manageable limits has been part of go-libp2p, this component was designed to handle the regular churn of peers, not a targeted resource exhaustion attack.
In the original version of the attack, the malicious node would continue opening new streams on a stream multiplexer that doesn’t provide sufficient back pressure (yamux or mplex). It is easy to defend against this one attack, but there are countless variations of this attack:
- Opening streams and causing a non-trivial memory allocation (e.g., for multistream or protobuf parsing)
- Creating a lot of sybil nodes and opening new connections across nodes
Patches (What to do as a go-libp2p consumer:)
-
Update your go-libp2p dependency to go-libp2p v0.18.0 or greater (current version as of publish date is v0.24.0.)
- Note: It's recommend that you update to
v0.21.0 onwards as you’ll get some useful functionality that will help in production environments like better metrics around resource usage, Grafana dashboards around resource usage, allow list support, and default autoscaling limits. Please see the v0.21.0 release notes for more info.)
-
Determine appropriate limits for your application - go-libp2p sets up a resource manager with the default limits if none are provided. For default definitions please see limits_defaults.go. These limits are also set to automatically scale, this is done using the AutoScale method of the ScalingLimitConfig. We recommend you tune your limits as described here.
-
Configure your node to be attack resilient. See how to respond to an attack and identify misbehaving peers here. Then setup automatic blocking with fail2ban using canonical libp2p log lines: guide on how to do so here.
Examples
Note: go-libp2p still implements the connection manager mentioned above. The connection manager is a component independent of the resource manager, which aims to keep the number of libp2p connections between a low and a high watermark. When modifying connection limits, it’s advantageous to keep the configuration of these components consistent, i.e., when setting a limit of N concurrent connections in the resource manager, the high watermark should be at most (and ideally slightly less) than N.
Workarounds
Although there are no workarounds within go-libp2p, some range of attacks can be mitigated using OS tools (like manually blocking malicious peers using iptables or ufw ) or making use of a load balancer in front of libp2p nodes.
However these require direct action & responsibility on your part and are no substitutes for upgrading go-libp2p. Therefore, we highly recommend upgrading your go-libp2p version for the way it enables tighter scoped limits and provides visibility into and easier reasoning about go-libp2p resource utilization.
References
Please see our DoS Mitigation page for more information on how to incorporate mitigation strategies, monitor your application, and respond to attacks: https://docs.libp2p.io/reference/dos-mitigation/.
Please see the related disclosure for rust-libp2p: https://github.com/libp2p/rust-libp2p/security/advisories/GHSA-jvgw-gccv-q5p8 and js-libp2p: https://github.com/libp2p/js-libp2p/security/advisories/GHSA-f44q-634c-jvwv
For more information
If you have any questions or comments about this advisory email us at security@libp2p.io
Latest trending attack
Criticalyesterday
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.
