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

Published May 22, 2026
·
Updated

Invoking server panic during CheckHostKey/Authenticate in golang.org/x/crypto/ssh

Other sources

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.

— MITRE

Affected Software

33 affected componentsFixes available
golang.org/x/crypto/ssh
Microsoft azl3 kubevirt 1.7.1-2
Patch available
Microsoft azl3 cert-manager 1.12.15-6
Patch available
Microsoft azl3 packer 1.9.5-13
Patch available
Microsoft azl3 kubernetes 1.30.10-23
Patch available
Microsoft azl3 moby-engine 25.0.3-17
Patch available
Microsoft azl3 moby-engine 25.0.3-18
Patch available
Microsoft azl3 kubernetes 1.30.10-25
Patch available
Microsoft azl3 docker-compose 2.27.0-11
Patch available
Microsoft azl3 gh 2.62.0-16
Patch available
Microsoft azl3 cf-cli 8.7.11-6
Patch available
Microsoft azl3 telegraf 1.31.0-22
Patch available
Microsoft azl3 docker-buildx 0.14.0-13
Patch available
go/golang.org/x/crypto/ssh<0.52.0
0.52.0
Golang Crypto Go<0.52.0
Microsoft azl3 telegraf 1.31.0-23<1.31.0-23
1.31.0-23
Microsoft azl3 gh 2.62.0-17<2.62.0-17
2.62.0-17
Microsoft azl3 docker-buildx 0.14.0-13<0.14.0-15
0.14.0-15
Microsoft azl3 cf-cli 8.7.11-7<8.7.11-7
8.7.11-7
Microsoft azl3 telegraf 1.31.0-22<1.31.0-23
1.31.0-23
Microsoft azl3 moby-engine 25.0.3-18<25.0.3-18
25.0.3-18
Microsoft azl3 gh 2.62.0-16<2.62.0-17
2.62.0-17
Microsoft azl3 cf-cli 8.7.11-6<8.7.11-7
8.7.11-7
Microsoft azl3 kubernetes 1.30.10-25<1.30.10-25
1.30.10-25
Microsoft azl3 docker-compose 2.27.0-11<2.27.0-13
2.27.0-13
Microsoft azl3 packer 1.9.5-13<1.9.5-14
1.9.5-14
Microsoft azl3 moby-engine 25.0.3-17<25.0.3-18
25.0.3-18
Microsoft azl3 cert-manager 1.12.15-6<1.12.15-8
1.12.15-8
Microsoft azl3 kubernetes 1.30.10-23<1.30.10-25
1.30.10-25
Microsoft azl3 kubevirt 1.7.1-2<1.7.1-5
1.7.1-5
Microsoft azl3 gh 2.62.0-18<2.62.0-17
2.62.0-17
IBM Db2 Genius Hub<=1.1, 1.1.1, 1.1.2
IBM Agentics<=1.0

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade go/golang.org/x/crypto/ssh to a version that resolves this vulnerability.

    Fixed in 0.52.0
  2. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 1.31.0-23
  3. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 2.62.0-17
  4. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 0.14.0-15
  5. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 8.7.11-7
  6. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 25.0.3-18
  7. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 1.30.10-25
  8. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 2.27.0-13
  9. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 1.9.5-14
  10. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 1.12.15-8
  11. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 1.7.1-5

Event History

May 22, 2026
CVE Published
via MITRE·02:31 AM
Data Sourced
via MITRE·02:31 AM
DescriptionWeakness
Data Sourced
via Red Hat·04:01 AM
DescriptionSeverityAffected Software
Data Sourced
via NVD·04:16 AM
DescriptionSeverityWeaknessAffected Software
May 27, 2026
Data Sourced
via Microsoft·08:15 AM
DescriptionSeverityWeaknessAffected Software
Updated
via Microsoft·08:15 AM
Affected Software
Updated
via Microsoft·08:15 AM
DescriptionSeverity
Jun 25, 2026
Advisory Published
via GitHub·10:15 PM
Data Sourced
via GitHub·10:15 PM
DescriptionSeverityWeaknessAffected Software
Jul 13, 2026
Data Sourced
via IBM·12:00 AM
DescriptionAffected Software

Parent advisories

This vulnerability appears in the following advisories.

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Frequently Asked Questions

1

What is the severity of CVE-2026-39835?

The severity of CVE-2026-39835 is rated as 33 on a risk scale.

2

How do I fix CVE-2026-39835?

To fix CVE-2026-39835, ensure that the IsUserAuthority or IsHostAuthority callbacks are set when using CertChecker.

3

What systems are affected by CVE-2026-39835?

CVE-2026-39835 affects SSH servers utilizing the CertChecker from golang.org/x/crypto/ssh.

4

What type of vulnerability is CVE-2026-39835?

CVE-2026-39835 is classified as a Null Pointer Dereference vulnerability.

5

What happens if CVE-2026-39835 is exploited?

Exploitation of CVE-2026-39835 can cause the SSH server to panic, resulting in a denial of service.

Company

Resources

Contact

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