CVE-2026-32314 — yamux
CVE-2026-32314 is a CWE-248 vulnerability in yamux. A fix is available for yamux — see the affected versions and patch details below.
Yamux remote Panic via malformed Data frame with SYN set and len = 262145
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- 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 CVE-2026-32314.
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
Summary
The Rust implementation of Yamux can panic when processing a crafted inbound Data frame that sets SYN and uses a body length greater than DEFAULT_CREDIT (e.g. 262145). On the first packet of a new inbound stream, stream state is created and a receiver is queued before oversized-body validation completes. When validation fails, the temporary stream is dropped and cleanup may call remove(...).expect("stream not found"), triggering a panic in the connection state machine. This is remotely reachable over a normal Yamux session and does not require authentication. kind of vulnerability is it? Who is
Attack Scenario
An attacker that can establish a Yamux session with a target node can crash the target by sending a single validly encoded Yamux Data|SYN frame with an oversized body:
- Establish a standard authenticated transport session that negotiates Yamux.
- Send one Yamux frame with:
- Tag = Data
- Flags = SYN
- StreamId = 1 (or any new inbound stream id)
- Length = DEFAULT_CREDIT + 1 (e.g. 262145)
- Body of matching size This can trigger a panic (stream not found) and terminate the process, depending on host application panic policy.
Patches
Users should upgrade to yamux v0.13.10
This vulnerability was originally submitted by @revofusion to the Ethereum Foundation bug bounty program
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | yamux | all versions | 0.13.10cargo update -p yamux --precise 0.13.10 |
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 0.13.10 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-32314 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 CVE-2026-32314 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-32314. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-32314 in your dependencies?
O3 Security finds CVE-2026-32314 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.