5.3

CVE-2026-39835: Invoking server panic during CheckHostKey/Authenticate in golang.org/x/crypto/ssh

Modified
AliasesUBUNTU-CVE-2026-39835DEBIAN-CVE-2026-39835CGA-227c-6fj5-2f4q
Published 22-05-2026Last modified 18-09-2026

Vulnerability summary

CVE-2026-39835 is a medium (CVSS 5.3) Improper Certificate Validation vulnerability in golang crypto. EPSS estimates a 0.50% chance of exploitation in the next 30 days, higher than 43.1% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 5.3, network access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
5.3/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.50%
0%100%
Low · -0.16 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 63 · Related 64
OPENSUSE-SU-2026:10842-1OPENSUSE-SU-2026:10845-1OPENSUSE-SU-2026:10856-1OPENSUSE-SU-2026:10949-1OPENSUSE-SU-2026:11126-1OPENSUSE-SU-2026:11806-1

Timeline

  1. 22-05-2026
    PublishedVulnerability first disclosed.
  2. 18-09-2026
    Last modifiedVulnerability information updated.

Description

SSH servers which use CertChecker as a public key callback without setting IsUserAuthority or IsHostAuthority could be caused to panic by a client presenting a certificate. CertChecker now returns an error instead of panicking when these callbacks are nil.

CVSS metrics

7 scores · 7 sources · 1 version

EPSS trend

Probability

0.50%

Chance of exploitation in the next 30 days

Percentile

43%

Versus all other CVEs

30-day change

Decrease -0.16 pp

From 0.66% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Chainguard200 products
  • aactl< 0.4.12-r53
  • act< 0.2.88-r6
  • actions-runner-controllerAll versions (No fix recorded)
  • actions-runner-controller-fipsAll versions (No fix recorded)
  • ageAll versions (No fix recorded)

1 vendor · 200 products · Showing 200 of 2856

References

66 links
Show all 66 references