CVE-2026-39834: critical vulnerability in golang.org/x/crypto/ssh
Invoking infinite loop on large channel writes in golang.org/x/crypto/ssh
Published
28Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 9.1epss 0.6%
exploitation probability
0.6%top 52% of all CVEs
observed exploitation
nono source reports it
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:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Affected products
golang.org/x/crypto · golang.org/x/crypto/sshRelated CVEs — golang.org/x/crypto/ssh
In the same product, most dangerous first.
CVE-2024-45337CRITICALMisuse of connection.serverAuthenticate may cause authorization bypass in golang.org/x/cryptoEPSS 3.2%CVE-2025-22869HIGHPotential denial of service in golang.org/x/cryptoEPSS 0.9%CVE-2026-39830CRITICALInvoking client can cause server deadlock on unexpected responses in golang.org/x/crypto/sshEPSS 0.7%CVE-2025-58181MEDIUMUnbounded memory consumption in golang.org/x/crypto/sshEPSS 0.6%CVE-2026-46595CRITICALInvoking VerifiedPublicKeyCallback permissions skip enforcement in golang.org/x/crypto/sshEPSS 0.6%CVE-2026-39835MEDIUMInvoking server panic during CheckHostKey/Authenticate in golang.org/x/crypto/sshEPSS 0.5%