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CVE-2026-39830VulnerabilityPublished Updated

Microsoft · Invoking client can cause server deadlock on unexpected responses in golang.org/x/crypto/ssh

Affects MicrosoftSource GCVE Database

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Authoritative record:CVE-2026-39830· Critical 9.1

Not known to be exploited · CVSS 9.1 Critical : upgrade to 0.52.0 as a priority.

Data as of 31 Oct 2026, 08:36 UTC

CVSS 3.1 base score
9.1Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.6% chance of exploitation in 30 days – higher than 52% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 0.52.0
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 22 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade golang.org/x/crypto/ssh to 0.52.0.

Affected software

ProductAffectedFixed in
golang.org/x/cryptogolang.org/x/crypto/sshAffected
  • <0.52.0
Fixed in
  • 0.52.0
Gogolang.org/x/crypto/sshpkg:golang/golang.org/x/crypto/sshOther threatsAffected
  • =0
Fixed in–
Gogolang.org/x/crypto/sshpkg:golang/golang.org/x/crypto/sshOther threatsAffected
  • <0.52.0
Fixed in
  • 0.52.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

A vulnerability in golang.org/x/crypto/ssh version 3.0 can cause a server deadlock when the client sends unexpected responses. This issue may impact server availability by causing it to become unresponsive.

References

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