GO · JUNE 2026 · EARLY WARNING

golang.org/x/crypto: Potential Server Deadlock on Unexpected Responses

EARLY WARNING · UNCONFIRMED. This page describes a developing threat that 0Day surfaced from early signals and has not yet independently confirmed. Details may change. Always verify against the primary sources before acting.
GHSA-VGWF-H737-FF37Severity: HIGH

An early warning has been issued regarding a potential vulnerability in golang.org/x/crypto that could allow a malicious SSH peer to cause a server deadlock by sending unsolicited global request responses.

What happened

Reportedly, a malicious SSH peer could exploit a vulnerability in golang.org/x/crypto by sending unsolicited global request responses, which could fill an internal buffer and block the connection's read loop. This blocked goroutine may not be released by calling Close(), resulting in a resource leak per connection. To mitigate this risk, unsolicited global responses are now discarded.

The vulnerability appears to affect various versions of golang.org/x/crypto, with fixes available in versions such as 0.0.0-20201216223049-8b5274cf687f, 0.52.0, 0.17.0, and others. The exact versions introduced and fixed are detailed in the provided data.

Professional software engineers using golang.org/x/crypto are advised to upgrade to the latest version to mitigate the risk of server deadlock. For more detailed information, consult the primary sources listed.

How 0Day mitigates this

MATCHED TO YOUR ACTUAL DEPENDENCY GRAPH0Day matches every incoming threat signal against your GitHub organization’s full dependency graph, including transitive dependencies. If golang.org/x/crypto is anywhere in your dependency tree, the engineers who own the affected repositories get a push alert the moment it is flagged — no manual audit to remember to run.

Read how this differs from waiting on a scanner to catch a known advisory, or see the exact, read-only access 0Day needs to do this for an organization.

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