CVE-2026-76835

CRITICALPre-NVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

Score 9.1 from GitHub Security Advisory (severity: CRITICAL) published 2026-08-24. A secondary CVSS source baseline 9.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this weekElevated
9.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 9.1Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

OAuth2 Proxy honours a client-supplied X-Forwarded-Uri header when deciding whether a request may skip authentication, because the guard added for CVE-2026-40575 is inert in the default reverse-proxy configuration. GetRequestURI in pkg/requests/util/util.go prefers that header over the real request URI whenever CanTrustForwardedHeaders returns true, and isAllowedPath in oauthproxy.go matches the skip_auth_routes and skip_auth_regex allow list against the resulting path. CanTrustForwardedHeaders in pkg/apis/middleware/scope.go grants that trust when the caller's address is in the trusted proxy set, and buildTrustedProxyNetSet falls back to defaultTrustedProxyIPs, which is 0.0.0.0/0 and ::/0, whenever reverse proxy mode is enabled without trusted_proxy_ip configured. Every client is therefore treated as a trusted proxy. An unauthenticated attacker can request a protected upstream path while setting X-Forwarded-Uri to a value matching an allow-listed route, so the skip-auth decision is made against the spoofed value while the upstream receives the protected path unchanged.

CVSS v3
9.1
EG Score
9.1CRITICALmedium confidence
EG Risk
72
EG Risk 72/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity91% × 45%
Exploitation40% × 40%
Automatability100% × 15%
CISA SSVC: Track at low, Track* at medium and Attend at high mission impact.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.5%
EPSS %ILE
37th
KEV
Not listed

CISA SSVCTrack at low, Track* at medium and Attend at high mission impact.

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

August 24, 2026

Last Modified

October 8, 2026

Advisory Details (5)

Auto-updated Sep 15, 2026
Patch available. Sources: github.
generic

OAuth2 Proxy 7.15.2 through 7.15.4 Authentication Bypass via X-Forwarded-Uri Under the Default Trusted Proxy Set | Advisories | VulnCheck

https://www.vulncheck.com/advisories/oauth2-proxy-through-authentication-bypass-via-x-forwarded-uri-under-the-default-trusted-proxy-set
githubMentions a patch (unverified)

Authentication Bypass via X-Forwarded-Uri Header Spoofing · Advisory · oauth2-proxy/oauth2-proxy · GitHub

https://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-7x63-xv5r-3p2x
generic

oauth2-proxy/pkg/apis/middleware/scope.go at v7.15.4 · oauth2-proxy/oauth2-proxy · GitHub

https://github.com/oauth2-proxy/oauth2-proxy/blob/v7.15.4/pkg/apis/middleware/scope.go
generic

[Bug]: Auth bypass: spoofed X-Forwarded-Uri skips auth for protected upstream paths under default reverse-proxy config · Issue #3506 · oauth2-proxy/oauth2-proxy · GitHub

https://github.com/oauth2-proxy/oauth2-proxy/issues/3506
generic

GitHub - oauth2-proxy/oauth2-proxy: A reverse proxy that provides authentication with Google, Azure, OpenID Connect and many more identity providers. · GitHub

https://github.com/oauth2-proxy/oauth2-proxy

Vendor Advisories for CVE-2026-76835(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatoauth2-proxy-main-7.15.5-0.1.hum12026-10-01redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(2 across 1 ecosystem)
Go(2)
PackageVulnerable rangeFix by version rangeDependents
github.com/oauth2-proxy/oauth2-proxy—
  • every version on: no fix on record
—
github.com/oauth2-proxy/oauth2-proxy/v7—
  • 7.5.0 up to 7.15.2: fixed in 7.15.2
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 71× in last 7d / 249× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 394 total refreshes for this CVE.

  1. 2026-10-10 20:00 UTCEPSS rescore
  2. 2026-10-10 16:23 UTCVendor advisory
  3. 2026-10-10 16:23 UTCGHSA enrichment
  4. 2026-10-10 12:33 UTCEG score recompute
  5. 2026-10-10 12:33 UTCVendor advisory
  6. 2026-10-10 12:32 UTCGHSA enrichment
  7. 2026-10-09 20:07 UTCEPSS rescore
  8. 2026-10-09 08:24 UTCVendor advisory
  9. 2026-10-09 08:24 UTCGHSA enrichment
  10. 2026-10-09 04:46 UTCEG score recompute
  11. 2026-10-09 04:46 UTCVendor advisory
  12. 2026-10-09 04:46 UTCGHSA enrichment
  13. 2026-10-08 17:13 UTCEPSS rescore
  14. 2026-10-08 16:36 UTCEG score recompute
  15. 2026-10-08 16:36 UTCVendor advisory
  16. 2026-10-08 16:36 UTCGHSA enrichment
  17. 2026-10-08 15:42 UTCEG score recompute
  18. 2026-10-08 15:42 UTCVendor advisory
  19. 2026-10-08 15:42 UTCGHSA enrichment
  20. 2026-10-08 07:29 UTCVendor advisory
  21. 2026-10-08 07:29 UTCGHSA enrichment
  22. 2026-10-08 03:50 UTCEG score recompute
  23. 2026-10-08 03:50 UTCVendor advisory
  24. 2026-10-08 03:50 UTCGHSA enrichment
  25. 2026-10-07 23:48 UTCEPSS rescore
Show 75 more
  1. 2026-10-07 10:25 UTCVendor advisory
  2. 2026-10-07 10:25 UTCGHSA enrichment
  3. 2026-10-07 06:41 UTCVendor advisory
  4. 2026-10-07 06:41 UTCGHSA enrichment
  5. 2026-10-07 03:03 UTCVendor advisory
  6. 2026-10-07 03:03 UTCGHSA enrichment
  7. 2026-10-06 23:25 UTCVendor advisory
  8. 2026-10-06 23:25 UTCGHSA enrichment
  9. 2026-10-06 19:48 UTCVendor advisory
  10. 2026-10-06 19:48 UTCGHSA enrichment
  11. 2026-10-06 16:10 UTCEG score recompute
  12. 2026-10-06 16:10 UTCVendor advisory
  13. 2026-10-06 16:10 UTCGHSA enrichment
  14. 2026-10-06 15:18 UTCEPSS rescore
  15. 2026-10-06 12:04 UTCVendor advisory
  16. 2026-10-06 12:04 UTCGHSA enrichment
  17. 2026-10-06 07:45 UTCVendor advisory
  18. 2026-10-06 07:45 UTCGHSA enrichment
  19. 2026-10-06 02:47 UTCVendor advisory
  20. 2026-10-06 02:47 UTCGHSA enrichment
  21. 2026-10-05 20:41 UTCEG score recompute
  22. 2026-10-05 20:41 UTCVendor advisory
  23. 2026-10-05 20:41 UTCGHSA enrichment
  24. 2026-10-05 17:43 UTCEPSS rescore
  25. 2026-10-05 17:04 UTCVendor advisory
  26. 2026-10-05 17:04 UTCGHSA enrichment
  27. 2026-10-05 12:22 UTCVendor advisory
  28. 2026-10-05 12:22 UTCGHSA enrichment
  29. 2026-10-05 08:44 UTCVendor advisory
  30. 2026-10-05 08:44 UTCGHSA enrichment
  31. 2026-10-05 05:04 UTCVendor advisory
  32. 2026-10-05 05:04 UTCGHSA enrichment
  33. 2026-10-05 01:26 UTCEG score recompute
  34. 2026-10-05 01:26 UTCVendor advisory
  35. 2026-10-05 01:26 UTCGHSA enrichment
  36. 2026-10-04 23:22 UTCEPSS rescore
  37. 2026-10-04 20:41 UTCVendor advisory
  38. 2026-10-04 20:41 UTCGHSA enrichment
  39. 2026-10-04 13:23 UTCVendor advisory
  40. 2026-10-04 13:23 UTCGHSA enrichment
  41. 2026-10-04 09:34 UTCVendor advisory
  42. 2026-10-04 09:34 UTCGHSA enrichment
  43. 2026-10-04 05:56 UTCVendor advisory
  44. 2026-10-04 05:56 UTCGHSA enrichment
  45. 2026-10-04 02:18 UTCVendor advisory
  46. 2026-10-04 02:18 UTCGHSA enrichment
  47. 2026-10-03 20:14 UTCVendor advisory
  48. 2026-10-03 20:14 UTCGHSA enrichment
  49. 2026-10-03 16:31 UTCEG score recompute
  50. 2026-10-03 16:31 UTCVendor advisory
  51. 2026-10-03 16:31 UTCGHSA enrichment
  52. 2026-10-03 14:26 UTCEPSS rescore
  53. 2026-10-03 05:02 UTCVendor advisory
  54. 2026-10-03 05:02 UTCGHSA enrichment
  55. 2026-10-03 01:11 UTCVendor advisory
  56. 2026-10-03 01:11 UTCGHSA enrichment
  57. 2026-10-02 21:33 UTCEG score recompute
  58. 2026-10-02 21:33 UTCVendor advisory
  59. 2026-10-02 21:33 UTCGHSA enrichment
  60. 2026-10-02 17:43 UTCVendor advisory
  61. 2026-10-02 17:43 UTCGHSA enrichment
  62. 2026-10-02 14:04 UTCVendor advisory
  63. 2026-10-02 14:03 UTCGHSA enrichment
  64. 2026-10-02 10:20 UTCGHSA enrichment
  65. 2026-10-02 06:42 UTCGHSA enrichment
  66. 2026-10-02 01:18 UTCGHSA enrichment
  67. 2026-10-01 21:02 UTCEG score recompute
  68. 2026-10-01 21:02 UTCGHSA enrichment
  69. 2026-10-01 19:50 UTCEPSS rescore
  70. 2026-10-01 12:53 UTCGHSA enrichment
  71. 2026-10-01 09:16 UTCGHSA enrichment
  72. 2026-10-01 05:37 UTCGHSA enrichment
  73. 2026-10-01 01:08 UTCGHSA enrichment
  74. 2026-09-30 20:17 UTCEG score recompute
  75. 2026-09-30 20:17 UTCGHSA enrichment

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2026-76835?
CVE-2026-76835 is a critical vulnerability published on August 24, 2026. OAuth2 Proxy honours a client-supplied X-Forwarded-Uri header when deciding whether a request may skip authentication, because the guard added for CVE-2026-40575 is inert in the default reverse-proxy configuration. GetRequestURI in pkg/requests/util/util.go prefers that header over the real request…
When was CVE-2026-76835 disclosed?
CVE-2026-76835 was first published on August 24, 2026, with the most recent update on October 8, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-76835 actively exploited?
CVE-2026-76835 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (37th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-76835?
CVE-2026-76835 has a CVSS base score of 9.1 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-76835?
A fix for CVE-2026-76835 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-76835 are linked in the Vendor Advisories panel on this page.

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