onyx

onyx --cves cve-2026-39858

CVE-2026-39858

CRITPOCTraefik
score
0.5
cvss
10.0
epss
0.6%
published
2026-04-30
kev added
—
first seen

Traefik < 2.11.43, 3.6.14, and 3.7.0-rc.2 contains an authentication bypass caused by improper sanitization of forwarded-header alias variants with underscores in ForwardAuth and snippet-based middleware, letting attackers spoof trust context and bypass authentication without valid credentials.

Timeline

How this CVE moved toward exploitation. Chart: last 30 days — trend score, EPSS, community mentions per day; hover the event lane.

events2026-04-30 — PublishedP2026-10-21 — Tracked by OnyxT2026-10-21 — Public PoCXscore2026-10-21: score 0.50.5epss2026-09-22: epss 0.5%2026-09-23: epss 0.5%2026-09-24: epss 0.6%2026-09-25: epss 0.6%2026-09-26: epss 0.6%2026-09-27: epss 0.6%2026-09-29: epss 0.6%2026-09-30: epss 0.6%2026-10-01: epss 0.6%2026-10-02: epss 0.6%2026-10-03: epss 0.6%2026-10-04: epss 0.6%2026-10-05: epss 0.6%2026-10-06: epss 0.6%2026-10-07: epss 0.6%2026-10-08: epss 0.6%2026-10-09: epss 0.6%2026-10-10: epss 0.6%2026-10-11: epss 0.6%2026-10-12: epss 0.6%2026-10-13: epss 0.6%2026-10-14: epss 0.6%2026-10-15: epss 0.6%2026-10-16: epss 0.6%2026-10-18: epss 0.6%2026-10-19: epss 0.6%2026-10-20: epss 0.6%2026-10-21: epss 0.6%0.6%mentions/day0no mentions in 30 days2026-09-22today
  1. Published
  2. Tracked by Onyx
  3. Public PoC

Exploit availability

Public PoC flagged by vulnx; no direct exploit link among the citations.

Weaknesses

CWE-290 CWE-289

References 8