HighCVECVE-2026-123158
[CVE-2026-123158] OpenBSD OpenSSH — OpenBSD OpenSSH Unexpected Status Code or Return Value Vulnerability
CISA KEV·Source published ·1 min read
What happened?
OpenBSD OpenSSH on Linux contains an unexpected status code or return value vulnerability that could allow for authentication bypass. Required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable.
Key details
- The flaw occurs when the shared-fragment marker is not preserved during socket buffer coalescing.
- ESP input processing then decrypts shared fragments in place because of the missing marker.
- This vulnerability can be combined with CVE-2026-109618 and CVE-2026-109619 to implant PHP webshells.
- Forensic triage is required under BOD 26-04 for this vulnerability.
Affected
- Linux Kernel (open-source component used by multiple products).
Fixes and mitigations
- Apply vendor mitigations per CISA BOD 26-04 guidance and referenced kernel commits.
Summarised by SecOraLens from CISA KEV. Always read the original source before acting. How SecOraLens verifies advisories.