High · CVSS 7.5CVE-2026-78662

Prevent DoS on deadlocked undecided channel in golang.org/x/crypto/sshCVE-2026-78662

Answer in brief

CVE-2026-78662 records a High severity (CVSS 7.5) vulnerability in Prevent DoS on deadlocked undecided channel in golang.org/x/crypto/ssh. The current sources do not mark it as known exploited. The current feed maps golang.org/x/crypto/golang.org/x/crypto/ssh (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 2, 2026Updated Sep 4, 2026Source checked Oct 18, 2026First seen by HOL Sep 2, 2026Material review Sep 4, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.5
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps golang.org/x/crypto/golang.org/x/crypto/ssh (generic). Check affected ranges and fixed versions before updating.

Affected products and reported versions
Product	Affected versions	Fixed versions
cpe:2.3:a:golang:crypto::::::go::*	Not reported	Not reported

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
golang.org/x/crypto/golang.org/x/crypto/sshgeneric	>=0 <0.56.0	0.56.0

Recommended response

Check inventory. Check lockfiles and deployed manifests for golang.org/x/crypto/golang.org/x/crypto/ssh.
Review the reported fix. Update golang.org/x/crypto/golang.org/x/crypto/ssh to 0.56.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 2, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 4, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 2, 2026

Sources and claim methodology

Upstream source description

Previously, a channel registered in the mux's chanList is not usable until it is established. A malicious peer was able flood the channel's incomingRequests, deadlocking the entire connection. Now, we add an atomic established state, set when a channel becomes usable. Until such a time, handlePacket drops every packet other than the open confirmation/failure, without blocking and without tearing down the connection.

Quoted source text, attributed separately from HOL analysis.