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CVE-2026-39834

CRITICALCVSS 9.1/10EPSS 0.47%

Last modified

CVE-2026-39834 is a critical-severity vulnerability rated 9.1/10 on the CVSS scale. 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.. EPSS estimates a 0.47% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
9.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

EPSS Probability
0.47%

36.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
GolangCrypto< 0.52.0

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2026-39834?
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.
How severe is CVE-2026-39834?
CVE-2026-39834 has a CVSS score of 9.1/10 (CRITICAL severity). The EPSS model estimates a 0.47% probability of exploitation in the next 30 days.
How do I fix CVE-2026-39834?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-39834?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST