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GHSA-4w32-2493-32g7

HighCVSS 8.7 / 10

Published Mar 13, 2026·Last modified Mar 16, 2026

Affected Components(0)

No affected components available

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

Risk Scores

Base Score

8.7

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability.

Threat Intelligence

6.6

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS

N/A

Probability that this vulnerability will be exploited in the wild within the next 30 days.

Exploit

Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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