Reference page — cumulative record through Sunday, October 4, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-73311

CVE-2026-73311CRITICAL

XenForo < 2.3.13 OAuth2 Authorization Code Reuse

  AV  AC  AT  PR  UI  VC  VI  VA   CVSS    EPSS   %ile   KEV
   N   H   N   N   N   H   H   N    9.1   .0050   40.5     —

AFFECTED
  Product  Versions     Fixed
  XenForo  unspecified  —

TIMELINE
  Aug 11  Reserved by VulnCheck
  Sep 8   Published (CNA: VulnCheck)
  Sep 9   EXPLOIT PUBLISHED — CVE-2026-73311 (XenForo). Public exploit reference added.
  Sep 10  EXPLOIT PUBLISHED — CVE-2026-73311 (XenForo). Public exploit reference added.
  Sep 11  EXPLOIT PUBLISHED — CVE-2026-73311 (XenForo). Public exploit reference added.

CWE-294 · CNA: VulnCheck · CVSS v4.0 · 5 references · NVD status: Analyzed

Description

XenForo before 2.3.13 contains an OAuth2 authorization code reuse vulnerability that allows attackers to obtain unauthorized token pairs by submitting a previously used authorization code. Attackers can exploit the failure to invalidate or mark authorization codes as consumed after initial token issuance to receive an independent token pair for the same user and scopes, bypassing the single-use guarantee of the OAuth2 authorization code flow.

Lifecycle

Complete event history — 5 events, chronological
Date	Event	Detail
August 11, 2026	Reserved	Reserved by VulnCheck
September 8, 2026	Published	Published (CNA: VulnCheck)
September 9, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-73311 (XenForo). Public exploit reference added.
September 10, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-73311 (XenForo). Public exploit reference added.
September 11, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-73311 (XenForo). Public exploit reference added.

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
XenForo	XenForo	—	—	—

Weaknesses

CWE-294

References (5)

https://bombobombone.github.io/posts/cve-2026-73311/ [technical-description]
https://github.com/BomboBombone/CVE-2026-73311 [exploit]
https://www.vulncheck.com/advisories/xenforo-oauth2-authorization-code-reuse [third-party-advisory]
https://xenforo.com/community/threads/security-fixes-released-for-all-xenforo-and-media-gallery-versions-2-2-0-2-3-12.239856/ [vendor-advisory, patch]
https://xenforo.com/community/threads/xenforo-2-3-13-and-add-ons-released-includes-security-fixes.239857/ [release-notes]

Authoritative record: CVE-2026-73311 at cve.org

Vendors: xenforo

Weaknesses: CWE-294

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-73311 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Sunday, October 4, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.