GHSA-4w32-2493-32g7 — yamux
Fix: libp2p/rust-yamux#221GHSA-4w32-2493-32g7 is a CWE-190 vulnerability in yamux. A fix is available for yamux — see the affected versions and patch details below.
Yamux vulnerable to remote Panic via malformed WindowUpdate credit
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-4w32-2493-32g7.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
yamuxReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
Sumary
The Rust implementation of Yamux accepts WindowUpdate credit values from the remote peer and applies them to per-stream send-window state.
A specially crafted WindowUpdate can cause arithmetic overflow in send-window accounting, which triggers a panic in the connection state machine. This is remotely reachable over a normal network connection and does not require authentication.
Attack Scenario
An attacker that can establish a Yamux session with a target node can crash the target by sending two validly encoded Yamux frames:
- Open a stream (e.g. DATA + SYN) so the stream exists with initial send-window state (
DEFAULT_CREDIT). - Send a WindowUpdate on that stream with a very large credit value (e.g. 0xFFFF_0000) such that adding credit to the current send-window overflows u32.
Impact
Remote unauthenticated denial of service.
An attacker can repeatedly trigger panics by reconnecting and replaying the crafted frame sequence.
Patches
Users should upgrade to yamux v0.13.9
This vulnerability was originally submitted by @revofusion to the Ethereum Foundation bug bounty program
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | yamux | ≥ 0.13.0&&< 0.13.9 | 0.13.9cargo update -p yamux --precise 0.13.9 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for yamux, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update yamux to 0.13.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4w32-2493-32g7 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-4w32-2493-32g7 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-4w32-2493-32g7. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-4w32-2493-32g7 in your dependencies?
O3 Security finds GHSA-4w32-2493-32g7 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.