by Kastro
Paper/Archive/CVE-2026-39834

CVE-2026-39834

golang.org/x/crypto golang.org/x/crypto/ssh — Invoking infinite loop on large channel writes in golang.org/x/crypto/ssh

EPSS 0.6%CVSS 9.1
critical.is priorityof 100
37
CVSS 9.1 (ADP)9.1 / 10 × 3027.3Not in CISA KEV+300.0EPSS percentile 48.6.486 × 209.7No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
golang.org/x/crypto/ssh< 0.52.00.52.0CNA

Scores by source

CISA ADP9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: partial

References

refgo.dev/issue/79567refgroups.google.com/g/golang-announce/c/a082jnz-LvIrefgo.dev/cl/781663refpkg.go.dev/vuln/GO-2026-5020