# CVE-2026-55706 — OpenBSD

> As of 2026-06-17, CVE-2026-55706 is a MEDIUM-severity vulnerability in OpenBSD, CVSS v3.1 5.8, EPSS 0.2% (14.6th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-55706, most recently “CVE-2026-55706: 27-Year-Old OpenBSD sppp(4) PAP Authentication Bypass in sppp_pap_input()”.

**Last updated:** 2026-06-17

## What is CVE-2026-55706?

sppp_pap_input in sys/net/if_spppsubr.c in OpenBSD before 076e2b1 allows authentication bypass via certain zero values for lengths.

The record classifies CVE-2026-55706 under weakness class [CWE-1284](https://intel.threadlinqs.com/cwe/CWE-1284). Its CVSS v3 base vector states that the flaw is reachable from an adjacent network, needs no prior authentication, needs no user interaction. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 110 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 5.8 — MEDIUM (`CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:L`)
- **EPSS (FIRST):** 0.2% probability of exploitation in the next 30 days, higher than 14.6% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 5.5/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-06-17

## Is CVE-2026-55706 being exploited?

Weaponised exploit code for CVE-2026-55706 is publicly available. 1 public proof-of-concept repository is tracked for this identifier.

- [trickest/cve](https://github.com/trickest/cve/blob/main/2026/CVE-2026-55706.md) (trickest)

## Affected products and versions

- **OpenBSD**: OpenBSD

## How to fix CVE-2026-55706

No vendor patch reference has been recorded for CVE-2026-55706 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-55706

1 tracked threat in the Threadlinqs corpus references CVE-2026-55706, either in the campaign’s CVE list or as an indicator on the campaign record.

- [CVE-2026-55706: 27-Year-Old OpenBSD sppp(4) PAP Authentication Bypass in sppp_pap_input()](https://intel.threadlinqs.com/threat/TL-2026-0881) — MEDIUM · 2026-06-17

## Sources

Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories, public proof-of-concept repositories. Last verified by Threadlinqs on 2026-06-21. This product uses the NVD API but is not endorsed or certified by the NVD.

**Other references**

- [blog.argus-systems.ai](https://blog.argus-systems.ai/blog/openbsd-pap-27-year-auth-bypass.html)
- [openwall.com](https://www.openwall.com/lists/oss-security/2026/06/16/9)
- [github.com](https://github.com/openbsd/src/commit/076e2b1c1fc4ac0883a72d3544131ad5cee7adf8)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-55706
Full detection coverage and IOCs for threats exploiting CVE-2026-55706 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp