EXECUTIVE SUMMARY:
Nine vulnerabilities have been identified in the golang.org/x/crypto/ssh package and its related components, affecting SSH authentication, authorization, cryptographic verification, agent forwarding, and protocol handling. The flaws include authorization and authentication bypasses, improper revocation validation, denial-of-service conditions, integer overflow, resource exhaustion, server-side panics, and failures to enforce security-key or agent constraints. Successful exploitation could allow attackers to bypass source-address restrictions, authenticate using revoked or unattended FIDO/U2F credentials, exhaust system resources, trigger application crashes, or weaken SSH key protections, ultimately impacting the confidentiality, integrity, and availability of Go-based SSH services.[/subscribe_to_unlock_form]
EXECUTIVE SUMMARY:
Nine vulnerabilities have been identified in the golang.org/x/crypto/ssh package and its related components, affecting SSH authentication, authorization, cryptographic verification, agent forwarding, and protocol handling. The flaws include authorization and authentication bypasses, improper revocation validation, denial-of-service conditions, integer overflow, resource exhaustion, server-side panics, and failures to enforce security-key or agent constraints. Successful exploitation could allow attackers to bypass source-address restrictions, authenticate using revoked or unattended FIDO/U2F credentials, exhaust system resources, trigger application crashes, or weaken SSH key protections, ultimately impacting the confidentiality, integrity, and availability of Go-based SSH services.[emaillocker id="1283"]
CVE-2026-46595 with a CVSS score of 10.0 – A permission enforcement flaw in golang.org/x/crypto/ssh allows the VerifiedPublicKeyCallback to bypass intended authorization checks, potentially granting users access with insufficient permission validation.
CVE-2026-42508 with a CVSS score of 9.1 – The golang.org/x/crypto/ssh/knownhosts package fails to enforce the @revoked marker, allowing revoked host keys to be accepted and enabling host authentication bypass.
CVE-2026-39834 with a CVSS score of 9.1 – An integer overflow in SSH channel write operations can trigger an infinite loop when handling data larger than 4 GB, resulting in a denial-of-service condition.
CVE-2026-39831 with a CVSS score of 9.1 – An authentication flaw in OpenSSH's FIDO/U2F security key verification allows signatures without physical user presence to be accepted, enabling unauthorized unattended authentication.
CVE-2026-39829 with a CVSS score of 7.5 – An input validation flaw in RSA and DSA public key parsing allows oversized key parameters to trigger excessive CPU consumption, leading to a denial-of-service condition during signature verification.
CVE-2026-39830 with a CVSS score of 9.1 – An SSH protocol handling flaw allows a malicious peer to send unsolicited global responses that block the connection's read loop, causing a per-connection resource leak and denial-of-service condition.
CVE-2026-46597 with a CVSS score of 7.5 – An integer casting flaw in the AES-GCM packet decoder allows specially crafted inputs to trigger a server-side panic, resulting in a denial-of-service condition.
CVE-2026-39832 with a CVSS score of 9.1 – An SSH agent constraint handling flaw allows destination restrictions to be stripped during remote key forwarding, enabling unrestricted use of forwarded keys.
CVE-2026-39833 with a CVSS score of 9.1 – An SSH keyring constraint enforcement flaw allows keys with the ConfirmBeforeUse restriction to sign without user confirmation, bypassing the intended security control.
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REFERENCES:
The following reports contain further technical details:
https://github.com/advisories/GHSA-x527-x647-q7gg
https://github.com/advisories/GHSA-5cgq-3rg8-m6cv
https://github.com/advisories/GHSA-rm3j-f69w-wqmq
https://github.com/advisories/GHSA-89gr-r52h-f8rx
https://github.com/advisories/GHSA-w879-237q-wc7r
https://github.com/advisories/GHSA-vgwf-h737-ff37
https://github.com/advisories/GHSA-q4h4-gmj2-qvw2
https://github.com/advisories/GHSA-f5wc-c3c7-36mc
https://github.com/advisories/GHSA-jppx-rxg9-jmrx