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Vulnerability record · CVE-2026-39834 · published 22 May 2026

CVE-2026-39834: Golang crypto integer overflow vulnerability

Golang · Crypto

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.

9.1 CVSS 3.1 Critical EPSS 0.64% · top 51.6% CWE-190 · Integer overflow
9.1CVSS 3.1 base score
0.64%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References
23 Jul 2026Last modified by NVD

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://go.dev/cl/781663 Issue Tracking
https://go.dev/issue/79567 Issue Tracking
https://groups.google.com/g/golang-announce/c/a082jnz-LvI Mailing List
https://pkg.go.dev/vuln/GO-2026-5020 Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-39834), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.