CVE-2026-39835: SSH servers which use CertChecker as a public key callback without setting IsUserAuthority or IsHostAuthority

Q: How do I fix CVE-2026-39835?

crypto: upgrade to 0.52.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-39835 being exploited?

CVE-2026-39835 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-39835 affect?

CVE-2026-39835 affects crypto. Severity is medium (CVSS 5.3). 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 ca

Q: How urgent is CVE-2026-39835?

Priority 34/100. Remotely exploitable, no login, no user action

Routine

MEDIUM 5.3REMOTEUPGRADE

CVE-2026-39835 is a medium-severity flaw (CVSS 5.3) affecting crypto. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 57%)
CISA exploited list	No
Weakness	CWE-295, CWE-476
Published	2026-05-22
Last modified	2026-09-18

Publisher (CNA): Go Project · Vendor: golang

Last updated 2026-09-18 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-22 04:16 UTCPublished CVE record published
2026-09-18 13:18 UTCUpdated Record last modified

golang crypto UPGRADE

Affected: < 0.52.0

Fixed in: 0.52.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy crypto || rpm -q crypto || crypto --version

2. UPGRADE to 0.52.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade crypto

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade crypto

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Advisories and coverage

Official advisories

AlmaLinux Errata: [ALSA-2026:37410] Important: buildah security update 2026-07-13
AlmaLinux Errata: [ALSA-2026:37123] Important: podman security, bug fix, and enhancement update 2026-07-13

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-39835?

crypto: upgrade to 0.52.0. Exact commands for each OS are on this page.

Is CVE-2026-39835 being exploited?

CVE-2026-39835 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-39835 affect?

CVE-2026-39835 affects crypto. Severity is medium (CVSS 5.3). 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 ca

How urgent is CVE-2026-39835?

Priority 34/100. Remotely exploitable, no login, no user action

Software pages

Go (Golang) vulnerabilities

Related CVEs

CVE-2026-39830 CRITICAL 9.1 UPGRADE A malicious SSH peer could send unsolicited global request responses to fill an internal buffer, blocking the
CVE-2026-39829 HIGH 7.5 UPGRADE The RSA and DSA public key parsers did not enforce size limits on key parameters
CVE-2026-42508 CRITICAL 9.1 UPGRADE Previously, a revoked 'SignatureKey' belonging to a CA was not correctly checked for revocation
CVE-2026-39832 CRITICAL 9.1 UPGRADE When adding a key to a remote agent constraint extensions such as restrict-destination-v00@openssh.com were no
CVE-2026-46595 CRITICAL 10.0 UPGRADE Previously, CVE-2024-45337 fixed an authorization bypass for misused ssh server configurations; if any other t

References

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