9.1

CVE-2026-39830: Invoking client can cause server deadlock on unexpected responses in golang.org/x/crypto/ssh

Modified
AliasesUBUNTU-CVE-2026-39830DEBIAN-CVE-2026-39830CGA-23f7-qg9g-pf46
Published 22-05-2026Last modified 18-09-2026

Vulnerability summary

CVE-2026-39830 is a critical (CVSS 9.1) vulnerability in golang crypto. EPSS estimates a 0.68% chance of exploitation in the next 30 days, higher than 52.5% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 9.1 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 1% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
9.1/10
010
Critical · v3.1 (CVE.org)
EPSS score
0.68%
0%100%
Low · +0.06 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 67 · Related 71
OPENSUSE-SU-2026:10856-1OPENSUSE-SU-2026:10949-1OPENSUSE-SU-2026:11031-1OPENSUSE-SU-2026:11046-1OPENSUSE-SU-2026:11053-1OPENSUSE-SU-2026:11126-1

Timeline

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

Description

A malicious SSH peer could send unsolicited global request responses to fill an internal buffer, blocking the connection's read loop. The blocked goroutine could not be released by calling Close(), resulting in a resource leak per connection. Unsolicited global responses are now discarded.

CVSS metrics

7 scores · 7 sources · 1 version

EPSS trend

Probability

0.68%

Chance of exploitation in the next 30 days

Percentile

53%

Versus all other CVEs

30-day change

Increase +0.06 pp

From 0.62% 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 2862

References

71 links
Show all 71 references