9.1

CVE-2026-39834: Invoking infinite loop on large channel writes in golang.org/x/crypto/ssh

Analyzed
AliasesUBUNTU-CVE-2026-39834DEBIAN-CVE-2026-39834CGA-227v-hc6p-jwx7
Published 22-05-2026Last modified 22-05-2026

Vulnerability summary

CVE-2026-39834 is a critical (CVSS 9.1) Integer Overflow or Wraparound vulnerability in golang crypto. EPSS estimates a 0.60% chance of exploitation in the next 30 days, higher than 48.6% 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
0.60%
0%100%
Low · -0.04 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 57 · Related 61
OPENSUSE-SU-2026:10843-1OPENSUSE-SU-2026:10856-1OPENSUSE-SU-2026:10858-1OPENSUSE-SU-2026:10889-1OPENSUSE-SU-2026:10949-1OPENSUSE-SU-2026:10966-1

Timeline

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

Description

When writing data larger than 4GB in a single Write call on an SSH channel, an integer overflow in the internal payload size calculation caused the write loop to spin indefinitely, sending empty packets without making progress. The size comparison now uses int64 to prevent truncation.

CVSS metrics

7 scores · 7 sources · 1 version

EPSS trend

Probability

0.60%

Chance of exploitation in the next 30 days

Percentile

49%

Versus all other CVEs

30-day change

Decrease -0.04 pp

From 0.64% 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 2860

References

15 links
Show all 15 references