CVE-2026-39834 — Vulnerability in golang.org/x/crypto — CVE Details

CRITICAL

golang.org/x/crypto vulnerable to infinite loop on large channel writes

Published June 25, 2026Updated September 10, 2026Source: osv

Summary

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.

Advisory Timeline

First published June 25, 2026 (109 days ago).
Last revised September 10, 2026 — 76 days after initial publication.

Remediation

Upgrade to the fixed version using your package manager.

Update golang.org/x/crypto to 0.52.0 or later

go get golang.org/x/crypto@v0.52.0

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (1)

Affects 1 ecosystem: go (1).

Package	Ecosystem	Affected	Fixed In
golang.org/x/crypto	go	All versions	0.52.0

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

CWE-190
Integer OverflowMITRE

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 9.1 score means for each attack dimension.

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

High

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

References

Frequently Asked Questions

What is CVE-2026-39834?: golang.org/x/crypto vulnerable to infinite loop on large channel writes This vulnerability has been assigned a severity rating of CRITICAL (CVSS score: 9.1/10).
How do I check if my project is affected by CVE-2026-39834?: CVE-2026-39834 affects golang.org/x/crypto. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2026-39834 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score

9.1

Exploitation is straightforward and causes maximum impact. Patch immediately.

Also Known As

GHSA-rm3j-f69w-wqmq

GO-2026-5020

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