🛡️ CVE-2026-31814 — yamux

🟠 CVSS 8.0 — High ⚠️ Exploit Public CWE-190 OSV
8.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

Yamux vulnerable to remote Panic via malformed WindowUpdate credit

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:

1. Open a stream (e.g. DATA + SYN) so the stream exists with initial send-window state (DEFAULT_CREDIT).

2. 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

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. Rated impact: confidentiality none, integrity none, availability high.

Weakness class

CVE-2026-31814 is classified as CWE-190: Integer Overflow or Wraparound. Arithmetic produces a value too large for its type and wraps around, so a later size or bounds check passes when it should not.

Affected software

CVE-2026-31814 is recorded against 1 package.

  • yamux

Timeline and source

Published on 13 March 2026 and last revised on 17 June 2026. A public exploit is known to exist, which raises the urgency of patching considerably. Record sourced from OSV.

References

github.com (Web)
nvd.nist.gov (Advisory)
github.com (Web)
github.com (Web)
github.com (Package)
github.com (Web)

CVE-2026-31814 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity HIGH
CVSS Score 8.0
CVSS Vector CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CWE CWE-190
Public Exploit ⚠️ Yes
Source OSV
Published 2026-03-13
Updated 2026-08-12
Modified 2026-06-17
Fix URL N/A

Affected Packages

Software From version Fixed in
yamux — —

Similar Threats

Exploit Protection

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CVE-2026-31814 carries CVSS 8.0 High rating and a public exploit already exists. BotEraser checks your installation against this and other known CVE records, and blocks IPs associated with exploit activity.

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