CVE-2026-39830

Modified Modified - Updated After Analysis

SSH Global Request Response Buffer Overflow in Go

Publication date: 2026-05-22

Last updated on: 2026-06-30

Assigner: Go Project

Description

A malicious SSH peer could send unsolicited global request responses to fill an internal buffer, blocking the connection's read loop. The blocked goroutine could not be released by calling Close(), resulting in a resource leak per connection. Unsolicited global responses are now discarded.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-05-22

Last Modified

2026-06-30

Generated

2026-07-02

AI Q&A

2026-05-22

EPSS Evaluated

2026-06-30

NVD

CVE-2026-39830

EUVD

EUVD-2026-31397

Affected Vendors & Products

Vendor	Product	Version / Range
golang	crypto	to 0.52.0 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-119	The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.
CWE-772	The product does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed.

Attack-Flow Graph

Executive Summary

This vulnerability occurs when a malicious SSH peer sends unsolicited global request responses to a Go SSH server, which fills an internal buffer and blocks the connection's read loop.

Because the read loop is blocked, the goroutine handling the connection cannot be released even if the connection is closed, leading to a resource leak for each affected connection.

The issue has been fixed by discarding unsolicited global responses to prevent the buffer from filling and blocking the read loop.

Impact Analysis

This vulnerability can cause resource leaks on the server handling SSH connections, as each malicious connection that sends unsolicited global request responses can block a goroutine indefinitely.

Over time, this can exhaust server resources, potentially leading to degraded performance or denial of service due to the accumulation of blocked goroutines.

Mitigation Strategies

To mitigate this vulnerability, update the golang.org/x/crypto package to version 0.52.0 or later, where unsolicited global SSH request responses are discarded to prevent resource leaks.

This fix addresses the issue by preventing the internal buffer from filling and blocking the connection's read loop, thus avoiding the resource leak per connection.

Compliance Impact

The provided information does not specify any direct impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.

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