CVE-2026-39834

Invoking infinite loop on large channel writes in golang.org/x/crypto/ssh

Published May 22, 2026 CVSS 3.1 · 9.1 Critical EPSS < 1% KEV · Not listed
Description
When writing data larger than 4GB in a single Write call on an SSH channel, an integer overflow in the internal payload size calculation caused the write loop to spin indefinitely, sending empty packets without making progress. The size comparison now uses int64 to prevent truncation.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-rm3j-f69w-wqmq golang.org/x/crypto vulnerable to infinite loop on large channel writes
Ubuntu USN Ubuntu USN USN-8447-2 LXD vulnerabilities
Ubuntu USN Ubuntu USN USN-8447-3 Google Guest Agent vulnerabilities
History
Type Values Removed Values Added
Weaknesses CWE-680
Type Values Removed Values Added
First Time appeared Golang crypto
Weaknesses CWE-190
CPEs cpe:2.3:a:golang:crypto:*:*:*:*:*:go:*:*
Vendors & Products Golang crypto
Type Values Removed Values Added
Weaknesses CWE-680
Type Values Removed Values Added
Weaknesses CWE-680
Type Values Removed Values Added
Metrics cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Golang
Golang ssh
Vendors & Products Golang
Golang ssh
Type Values Removed Values Added
Weaknesses CWE-680
Type Values Removed Values Added
Description When writing data larger than 4GB in a single Write call on an SSH channel, an integer overflow in the internal payload size calculation caused the write loop to spin indefinitely, sending empty packets without making progress. The size comparison now uses int64 to prevent truncation.
Title Invoking infinite loop on large channel writes in golang.org/x/crypto/ssh
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Go
Published
Updated
May 22, 2026, 6:50 PM
Reserved
Apr 7, 2026, 6:13 PM
Status
Analyzed
Published
May 22, 2026, 4:16 AM
Modified
Jul 23, 2026, 4:10 PM