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Noroxi
NVD / CVE Program· CNA Go

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

Noroxi assessment

Priority: Monitor (action score 21/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.50% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: golang.org/x/crypto golang.org/x/crypto/ssh 0.52.0; azl3 cert-manager 1.12.15-6 on Azure Linux 3.0 1.12.15-8; azl3 cf-cli 8.7.11-6 on Azure Linux 3.0 8.7.11-7.

Low priority for now. Upgrade to golang.org/x/crypto golang.org/x/crypto/ssh 0.52.0; azl3 cert-manager 1.12.15-6 on Azure Linux 3.0 1.12.15-8; azl3 cf-cli 8.7.11-6 on Azure Linux 3.0 8.7.11-7 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 5.3 · v3.1—No exploit Fix available
Published
May 22, 2026
Updated
Sep 18, 2026
EPSS
0.5% · 43th percentile

Report tools

JSON

Action score

21

Monitor

Low priority for now.

CVSS
21 / 40 · 5.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-39835

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
golangcrypto

Check your site's encryption

This vulnerability is about certificate validation or weak cryptography. The free SSL checker tests your certificate, enabled TLS versions and weak ciphers.

Run the SSL check

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • golang cryptobefore 0.52.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Go). Independent of NVD's CPE analysis and usually ahead of it.

  • golang.org/x/crypto golang.org/x/crypto/ssh

    • before 0.52.0affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:10buildahbefore 2:1.43.1-3.el10_22:1.43.1-3.el10_2
AlmaLinux:10buildah-testsbefore 2:1.43.1-3.el10_22:1.43.1-3.el10_2
AlmaLinux:8aardvark-dnsbefore 2:1.10.1-2.module_el8.10.0+4089+ce72bbbe2:1.10.1-2.module_el8.10.0+4089+ce72bbbe
AlmaLinux:8aardvark-dnsbefore 2:1.10.1-2.module_el8.10.0+3909+6e1c1eb72:1.10.1-2.module_el8.10.0+3909+6e1c1eb7
AlmaLinux:8aardvark-dnsbefore 2:1.10.1-2.module_el8.10.0+4047+545787c42:1.10.1-2.module_el8.10.0+4047+545787c4
AlmaLinux:8aardvark-dnsbefore 2:1.10.1-2.module_el8.10.0+3901+4b80ecd72:1.10.1-2.module_el8.10.0+3901+4b80ecd7
AlmaLinux:8buildahbefore 2:1.33.14-4.module_el8.10.0+4213+0493256b2:1.33.14-4.module_el8.10.0+4213+0493256b
AlmaLinux:8buildah-testsbefore 2:1.33.14-4.module_el8.10.0+4213+0493256b2:1.33.14-4.module_el8.10.0+4213+0493256b
AlmaLinux:8cockpit-podmanbefore 84.1-1.module_el8.10.0+4102+6c76e54484.1-1.module_el8.10.0+4102+6c76e544
AlmaLinux:8conmonbefore 3:2.1.10-1.module_el8.10.0+4090+919323383:2.1.10-1.module_el8.10.0+4090+91932338
AlmaLinux:8conmonbefore 3:2.1.10-1.module_el8.10.0+4068+0e21408f3:2.1.10-1.module_el8.10.0+4068+0e21408f
AlmaLinux:8conmonbefore 3:2.1.10-1.module_el8.10.0+3970+8445edf63:2.1.10-1.module_el8.10.0+3970+8445edf6
AlmaLinux:8container-selinuxbefore 2:2.229.0-3.module_el8.10.0+4213+0493256b2:2.229.0-3.module_el8.10.0+4213+0493256b
AlmaLinux:8containernetworking-pluginsbefore 1:1.4.0-8.module_el8.10.0+4136+164253431:1.4.0-8.module_el8.10.0+4136+16425343
AlmaLinux:8containers-commonbefore 2:1-82.module_el8.10.0+3876+e55593a82:1-82.module_el8.10.0+3876+e55593a8
AlmaLinux:8containers-commonbefore 2:1-82.module_el8.10.0+3901+4b80ecd72:1-82.module_el8.10.0+3901+4b80ecd7
AlmaLinux:8containers-commonbefore 2:1-82.module_el8.10.0+4089+ce72bbbe2:1-82.module_el8.10.0+4089+ce72bbbe
AlmaLinux:8critbefore 3.18-5.module_el8.10.0+3901+4b80ecd73.18-5.module_el8.10.0+3901+4b80ecd7
AlmaLinux:8critbefore 3.18-5.module_el8.10.0+4120+03ad4b473.18-5.module_el8.10.0+4120+03ad4b47
AlmaLinux:8critbefore 3.18-5.module_el8.10.0+4047+545787c43.18-5.module_el8.10.0+4047+545787c4
AlmaLinux:8critbefore 3.18-5.module_el8.10.0+3845+87b845523.18-5.module_el8.10.0+3845+87b84552
AlmaLinux:8criubefore 3.18-5.module_el8.10.0+3909+6e1c1eb73.18-5.module_el8.10.0+3909+6e1c1eb7
AlmaLinux:8criubefore 3.18-5.module_el8.10.0+4089+ce72bbbe3.18-5.module_el8.10.0+4089+ce72bbbe
AlmaLinux:8criubefore 3.18-5.module_el8.10.0+3876+e55593a83.18-5.module_el8.10.0+3876+e55593a8

+96

Same product

golang: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-46595Invoking VerifiedPublicKeyCallback permissions skip enforcement in golang.org/x/crypto/ssh
    40Plan
  • CVE-2026-42508Invoking auth bypass via unenforced @revoked status in golang.org/x/crypto/ssh/knownhosts
    38Monitor
  • CVE-2026-39834Invoking infinite loop on large channel writes in golang.org/x/crypto/ssh
    36Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-39832May 22, 2026 · Invoking agent constraints dropped when forwarding keys in golang.org/x/crypto/ssh/agent
    36Monitor
  • ← EarlierCVE-2026-39833May 22, 2026 · Invoking key constraints not enforced in golang.org/x/crypto/ssh/agent
    36Monitor
  • Later →CVE-2026-46597May 22, 2026 · Invoking byte arithmetic causes underflow and panic in golang.org/x/crypto/ssh
    30Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
golang.org/x/crypto golang.org/x/crypto/ssh0.52.0Vendor (CNA)
azl3 cert-manager 1.12.15-6 on Azure Linux 3.01.12.15-8 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 cf-cli 8.7.11-6 on Azure Linux 3.08.7.11-7 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 cf-cli 8.7.11-7 on Azure Linux 3.08.7.11-7 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 docker-buildx 0.14.0-13 on Azure Linux 3.00.14.0-15 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 docker-compose 2.27.0-11 on Azure Linux 3.02.27.0-13 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 gh 2.62.0-16 on Azure Linux 3.02.62.0-17 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 gh 2.62.0-17 on Azure Linux 3.02.62.0-17 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 gh 2.62.0-18 on Azure Linux 3.02.62.0-17 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 kubernetes 1.30.10-23 on Azure Linux 3.01.30.10-25 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 kubernetes 1.30.10-25 on Azure Linux 3.01.30.10-25 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 kubevirt 1.7.1-2 on Azure Linux 3.01.7.1-5 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 moby-engine 25.0.3-17 on Azure Linux 3.025.0.3-18 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 moby-engine 25.0.3-18 on Azure Linux 3.025.0.3-18 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 packer 1.9.5-13 on Azure Linux 3.01.9.5-14 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 telegraf 1.31.0-22 on Azure Linux 3.01.31.0-23 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 telegraf 1.31.0-23 on Azure Linux 3.01.31.0-23 · CBL-Mariner ReleasesMicrosoft (MSRC)
almalinux:aardvark-dns2:1.10.1-2.module_el8.10.0+3909+6e1c1eb7 · AlmaLinux:8Package registry (OSV)
almalinux:buildah2:1.43.1-3.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:buildah-tests2:1.43.1-3.el10_2 · AlmaLinux:10Package registry (OSV)
almalinux:cockpit-podman84.1-1.module_el8.10.0+4102+6c76e544 · AlmaLinux:8Package registry (OSV)
almalinux:conmon3:2.1.10-1.module_el8.10.0+3970+8445edf6 · AlmaLinux:8Package registry (OSV)
almalinux:container-selinux2:2.229.0-3.module_el8.10.0+4213+0493256b · AlmaLinux:8Package registry (OSV)
almalinux:containernetworking-plugins1:1.4.0-8.module_el8.10.0+4136+16425343 · AlmaLinux:8Package registry (OSV)
almalinux:podman6:5.8.2-4.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:podman-docker6:5.8.2-4.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:podman-plugins6:5.8.2-4.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:podman-remote6:5.8.2-4.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:podman-tests6:5.8.2-4.el9_8 · AlmaLinux:9Package registry (OSV)
debian:golang-go.crypto1:0.52.0-1 · Debian:14Package registry (OSV)

+50

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-425080 days apartInvoking auth bypass via unenforced @revoked status in golang.org/x/crypto/ssh/knownhosts
    38Monitor
  • CVE-2026-398280 days apartInvoking bypass of certificate restrictions in golang.org/x/crypto/ssh
    25Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
low · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
Low

Weakness class (CWE)

CWE-295 · Improper Certificate Validation

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

nvd-secondary

Root cause

A certificate validation error is silently swallowed instead of terminating the connection. Often, code added for a test environment makes its way into production.

The bug in code

The whole CWE-295 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

kotlin
override fun checkServerTrusted(chain: Array<X509Certificate>, type: String) {  // Left empty for the test environment}

Fixed

kotlin
val client = OkHttpClient.Builder()  .certificatePinner(    CertificatePinner.Builder()      .add("api.sirius.example", "sha256/…")      .build()  ).build()

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (19 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records