CVE-2026-56306

MEDIUMPre-NVD 6.46.4—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.4 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 84% 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, secondary
Elevated
6.4
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 6.4Exploit: NoneExposed: 0

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

Capgo before 12.128.2 contains a weak parsing vulnerability in the x-limited-key-id header that allows attackers to bypass subkey enforcement by submitting malformed values, zero, or duplicate headers that result in NaN or falsy values. Remote attackers can manipulate the x-limited-key-id header to disable limited key scoping and execute requests using the main API key context instead of restricted subkey permissions.

CVSS v3
6.4
EG Score
6.4(medium)
EPSS
16.4%
KEV
Not listed

Published

June 22, 2026

Last Modified

June 23, 2026

Advisory Details (2)

Auto-updated Jun 23, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

middlewareKey: x-limited-key-id weak parsing allows silent bypass/disable of subkey enforcement (NaN/0/duplicate header ambiguity) · Advisory · Cap-go/capgo · GitHub

https://github.com/Cap-go/capgo/security/advisories/GHSA-42vv-8j94-24wj
generic

Capgo - Subkey Enforcement Bypass via x-limited-key-id Header Parsing | Advisories | VulnCheck

https://www.vulncheck.com/advisories/capgo-subkey-enforcement-bypass-via-x-limited-key-id-header-parsing

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 19× in last 7d / 60× 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. 2026-07-15 18:54 UTCEG score recompute
  2. 2026-07-15 16:57 UTCEPSS rescore
  3. 2026-07-15 16:57 UTCEPSS rescore
  4. 2026-07-15 02:00 UTCEPSS rescore
  5. 2026-07-15 02:00 UTCEPSS rescore
  6. 2026-07-14 18:11 UTCEG score recompute
  7. 2026-07-13 22:31 UTCEPSS rescore
  8. 2026-07-13 16:57 UTCEG score recompute
  9. 2026-07-13 06:13 UTCEPSS rescore
  10. 2026-07-13 06:13 UTCEPSS rescore
  11. 2026-07-12 15:20 UTCEG score recompute
  12. 2026-07-12 05:46 UTCEPSS rescore
  13. 2026-07-11 14:36 UTCEG score recompute
  14. 2026-07-11 08:27 UTCEPSS rescore
  15. 2026-07-11 08:27 UTCEPSS rescore
  16. 2026-07-10 13:52 UTCEG score recompute
  17. 2026-07-09 19:10 UTCEPSS rescore
  18. 2026-07-09 19:10 UTCEPSS rescore
  19. 2026-07-09 13:01 UTCEG score recompute
  20. 2026-07-08 15:16 UTCEPSS rescore
  21. 2026-07-08 15:16 UTCEPSS rescore
  22. 2026-07-08 12:13 UTCEG score recompute
  23. 2026-07-07 13:46 UTCEPSS rescore
  24. 2026-07-07 13:46 UTCEPSS rescore
  25. 2026-07-07 11:05 UTCEG score recompute
Show 35 more
  1. 2026-07-06 16:27 UTCEPSS rescore
  2. 2026-07-06 16:27 UTCEPSS rescore
  3. 2026-07-06 09:38 UTCEG score recompute
  4. 2026-07-06 02:23 UTCEPSS rescore
  5. 2026-07-06 02:23 UTCEPSS rescore
  6. 2026-07-05 08:54 UTCEG score recompute
  7. 2026-07-05 02:31 UTCEPSS rescore
  8. 2026-07-05 02:30 UTCEPSS rescore
  9. 2026-07-04 08:10 UTCEG score recompute
  10. 2026-07-04 06:31 UTCEPSS rescore
  11. 2026-07-04 06:31 UTCEPSS rescore
  12. 2026-07-03 07:21 UTCEG score recompute
  13. 2026-07-02 06:37 UTCEG score recompute
  14. 2026-07-01 15:07 UTCEPSS rescore
  15. 2026-07-01 05:54 UTCEG score recompute
  16. 2026-06-30 23:22 UTCEPSS rescore
  17. 2026-06-30 05:09 UTCEG score recompute
  18. 2026-06-29 14:06 UTCEPSS rescore
  19. 2026-06-29 14:06 UTCEPSS rescore
  20. 2026-06-29 04:24 UTCEG score recompute
  21. 2026-06-28 14:07 UTCEPSS rescore
  22. 2026-06-28 04:56 UTCEPSS rescore
  23. 2026-06-28 04:56 UTCEPSS rescore
  24. 2026-06-28 03:39 UTCEG score recompute
  25. 2026-06-27 03:08 UTCEPSS rescore
  26. 2026-06-27 02:56 UTCEG score recompute
  27. 2026-06-26 02:13 UTCEG score recompute
  28. 2026-06-25 13:49 UTCEPSS rescore
  29. 2026-06-25 01:29 UTCEG score recompute
  30. 2026-06-24 14:05 UTCEPSS rescore
  31. 2026-06-24 00:46 UTCEG score recompute
  32. 2026-06-23 21:33 UTCEPSS rescore
  33. 2026-06-23 21:33 UTCEPSS rescore
  34. 2026-06-23 00:02 UTCEG score recompute
  35. 2026-06-23 00:00 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-56306?
CVE-2026-56306 is a medium vulnerability published on June 22, 2026. Capgo before 12.128.2 contains a weak parsing vulnerability in the x-limited-key-id header that allows attackers to bypass subkey enforcement by submitting malformed values, zero, or duplicate headers that result in NaN or falsy values. Remote attackers can manipulate the x-limited-key-id header to…
When was CVE-2026-56306 disclosed?
CVE-2026-56306 was first published in the National Vulnerability Database on June 22, 2026, with the most recent update on June 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-56306 actively exploited?
CVE-2026-56306 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 16.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-56306?
CVE-2026-56306 has a CVSS v3 base score of 6.4 (NVD).
How do I remediate CVE-2026-56306?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-56306, 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

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