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golang.org/x/crypto/ssh vulnerable to invoking bypass of certificate restrictions

Moderate severity GitHub Reviewed Published Jun 25, 2026 to the GitHub Advisory Database • Updated Jul 1, 2026

Package

gomod golang.org/x/crypto/ssh (Go)

Affected versions

< 0.52.0

Patched versions

0.52.0

Description

When an SSH server authentication callback returned PartialSuccessError with non-nil Permissions, those permissions were silently discarded, potentially dropping certificate restrictions such as force-command after a second factor succeeded. Returning non-nil Permissions with PartialSuccessError now results in a connection error.

References

Published by the National Vulnerability Database May 22, 2026
Published to the GitHub Advisory Database Jun 25, 2026
Reviewed Jun 25, 2026
Last updated Jul 1, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(13th percentile)

Weaknesses

Improper Preservation of Permissions

The product does not preserve permissions or incorrectly preserves permissions when copying, restoring, or sharing objects, which can cause them to have less restrictive permissions than intended. Learn more on MITRE.

Improper Certificate Validation

The product does not validate, or incorrectly validates, a certificate. Learn more on MITRE.

CVE ID

CVE-2026-39828

GHSA ID

GHSA-45gg-vh54-h5m9

Source code

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