CVE-2026-26308

HIGHNVD 8.28.2—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.2 under NVD CVSS v3. EPSS exploit probability: 0.3%, top 78% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
8.2EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.2Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Envoy is a high-performance edge/middle/service proxy. Prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13, the Envoy RBAC (Role-Based Access Control) filter contains a logic vulnerability in how it validates HTTP headers when multiple values are present for the same header name. Instead of validating each header value individually, Envoy concatenates all values into a single comma-separated string. This behavior allows attackers to bypass RBAC policies—specifically "Deny" rules—by sending duplicate headers, effectively obscuring the malicious value from exact-match mechanisms. This vulnerability is fixed in 1.37.1, 1.36.5, 1.35.8, and 1.34.13.

CVSS v3
8.2
EG Score
8.2(medium)
EG Risk
37(Track)
EG Risk 37/100SSVC: Track

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
Severity82% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
22%
KEV
Not listed

Published

March 10, 2026

Last Modified

June 17, 2026

Advisory Details (2)

Auto-updated Aug 2, 2026
Patch available. Sources: github_commit, github.
github Patch Available

RBAC Header Validation Bypass via Multi-Value Header Concatenation · Advisory · envoyproxy/envoy · GitHub

https://github.com/envoyproxy/envoy/security/advisories/GHSA-ghc4-35x6-crw5
github_commit

commit b6ba0b2294b9 (envoyproxy/envoy)

Fix landed in envoyproxy/envoy commit b6ba0b2294b9 — awaiting tagged release

https://github.com/envoyproxy/envoy/commit/b6ba0b2294b98484fb0ed8556897d1073cc27867

Vendor Advisories for CVE-2026-26308(1)

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

Affected Packages

(1 across 1 ecosystem)
Go(1)
PackageVulnerable rangeFixed inDependents
github.com/envoyproxy/envoy1.37.01.34.13—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 6× in last 7d / 27× 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.

  1. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-18 19:27 UTCEPSS rescore
  3. 2026-09-17 19:30 UTCEPSS rescore
  4. 2026-09-16 14:07 UTCEPSS rescore
  5. 2026-09-16 05:15 UTCEPSS rescore
  6. 2026-09-13 16:47 UTCEPSS rescore
  7. 2026-09-12 15:01 UTCEPSS rescore
  8. 2026-09-11 14:52 UTCEPSS rescore
  9. 2026-09-10 09:34 UTCEPSS rescore
  10. 2026-09-08 22:00 UTCEPSS rescore
  11. 2026-09-07 16:01 UTCEPSS rescore
  12. 2026-09-06 13:47 UTCEPSS rescore
  13. 2026-09-06 13:47 UTCEPSS rescore
  14. 2026-09-04 05:06 UTCEPSS rescore
  15. 2026-09-02 20:40 UTCOSV refresh
  16. 2026-09-02 14:11 UTCEPSS rescore
  17. 2026-09-01 13:53 UTCEPSS rescore
  18. 2026-09-01 04:39 UTCEPSS rescore
  19. 2026-08-30 19:17 UTCEPSS rescore
  20. 2026-08-30 01:22 UTCEPSS rescore
  21. 2026-08-28 21:41 UTCEPSS rescore
  22. 2026-08-27 14:25 UTCEPSS rescore
  23. 2026-08-26 14:46 UTCEPSS rescore
  24. 2026-08-25 13:48 UTCEPSS rescore
  25. 2026-08-23 00:19 UTCEPSS rescore
Show 35 more
  1. 2026-08-21 23:49 UTCEPSS rescore
  2. 2026-08-20 22:55 UTCEPSS rescore
  3. 2026-08-19 17:03 UTCEPSS rescore
  4. 2026-08-18 13:48 UTCEPSS rescore
  5. 2026-08-17 13:47 UTCEPSS rescore
  6. 2026-08-16 14:56 UTCEPSS rescore
  7. 2026-08-16 12:02 UTCEG score recompute
  8. 2026-08-16 02:14 UTCEPSS rescore
  9. 2026-08-15 01:30 UTCEPSS rescore
  10. 2026-08-14 07:58 UTCEG score recompute
  11. 2026-08-13 22:00 UTCEPSS rescore
  12. 2026-08-12 23:15 UTCEG score recompute
  13. 2026-08-12 13:50 UTCEPSS rescore
  14. 2026-08-11 21:57 UTCEG score recompute
  15. 2026-08-11 13:42 UTCEPSS rescore
  16. 2026-08-11 05:04 UTCEG score recompute
  17. 2026-08-11 00:00 UTCEPSS rescore
  18. 2026-08-09 19:10 UTCEG score recompute
  19. 2026-08-09 13:46 UTCEPSS rescore
  20. 2026-08-07 19:00 UTCEG score recompute
  21. 2026-08-06 20:00 UTCEG score recompute
  22. 2026-08-06 13:46 UTCEPSS rescore
  23. 2026-08-06 02:09 UTCEG score recompute
  24. 2026-08-05 19:17 UTCEPSS rescore
  25. 2026-08-04 15:10 UTCEPSS rescore
  26. 2026-08-04 01:29 UTCEG score recompute
  27. 2026-08-03 10:36 UTCEPSS rescore
  28. 2026-08-02 17:50 UTCEG score recompute▲ 0.70
  29. 2026-08-02 02:26 UTCEPSS rescore
  30. 2026-08-01 04:16 UTCEPSS rescore
  31. 2026-07-30 16:27 UTCEPSS rescore
  32. 2026-07-30 01:30 UTCEPSS rescore
  33. 2026-07-28 15:36 UTCEPSS rescore
  34. 2026-07-27 12:53 UTCEG score recompute
  35. 2026-07-27 12:50 UTCOSV refresh

Frequently asked(5)

What is CVE-2026-26308?
CVE-2026-26308 is a high vulnerability published on March 10, 2026. Envoy is a high-performance edge/middle/service proxy. Prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13, the Envoy RBAC (Role-Based Access Control) filter contains a logic vulnerability in how it validates HTTP headers when multiple values are present for the same header name. Instead of validating…
When was CVE-2026-26308 disclosed?
CVE-2026-26308 was first published in the National Vulnerability Database on March 10, 2026, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-26308 actively exploited?
CVE-2026-26308 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 77.9% of all scored CVEs.
What is the CVSS score of CVE-2026-26308?
CVE-2026-26308 has a CVSS v3 base score of 8.2 (NVD).
How do I remediate CVE-2026-26308?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-26308, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-26308

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