27 Years in the Dark: OpenBSD Fixes Ancient Remote Kernel Auth Bypass

Reddit •/u/Emergency_Stable_923 • June 16, 2026

Absolutely wild find by Argus-Systems. A remote authentication bypass hiding in OpenBSD's kernel PPP stack since it was imported from FreeBSD in July 1999. An attacker could essentially bypass authentication via a null-auth flaw and intercept/read PPPoE traffic without credentials. It survived every single release for nearly three decades until the patch. OpenBSD already released a patch. submitted by /u/Emergency_Stable_923 [link] [ ]

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This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

27-Year-Old OpenBSD Vulnerability Exposed: Remote Auth Bypass Disclosed A vulnerability in OpenBSD's networking stack has been disclosed, allowing attackers to bypass PAP authentication due to a logic flaw in the sppp_pap_input() function. This flaw, present since the import from FreeBSD in July 1999, enables attackers to intercept and read PPPoE traffic without credentials. The vulnerability affects systems relying on the Password Authentication Protocol (PAP) during the authentication phase. OpenBSD has released a patch to address this issue. The vulnerability has persisted through nearly three decades of system updates. Argus-Systems discovered the flaw, which is now classified as a critical security risk. Users of OpenBSD are urged to apply the patch immediately to mitigate potential exploitation. 3 sources 73

Extracted Entities

27 Years in the Dark: OpenBSD Fixes Ancient Remote Kernel Auth Bypass

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Extracted Entities

Attack Types (1)

CWE Weaknesses (1)

Platforms (2)