CVE-2026-42272
CVE-2026-42272 is a high-severity vulnerability with a CVSS 4.0 base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-178.
Key facts
- Severity: High (CVSS 4.0 base score 7.8)
- EPSS exploit prediction: 0% (32nd percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-28508
- Weakness: CWE-178
- Published:
- Last modified:
Description
Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. Prior to version 0.17.14, Heimdall handles URL-encoded slashes (%2F) in a case-sensitive manner, while percent-encoding is defined to be case-insensitive. As a result, the lowercase equivalent (%2f) is not recognized and therefore not processed as expected when allow_encoded_slashes is set to off (the default setting). This discrepancy can lead to differences in how request paths are interpreted by heimdall and upstream components, which may result in authorization bypass. This issue has been patched in version 0.17.14.
Frequently asked questions
- What is CVE-2026-42272?
- Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. Prior to version 0.17.14, Heimdall handles URL-encoded slashes (%2F) in a case-sensitive manner, while percent-encoding is defined to be case-insensitive. As a result, the lowercase equivalent (%2f) is not recognized and therefore not processed as expected when allow_encoded_slashes is set to off (the default setting). This discrepancy can lead to differences in how request paths are interpreted by heimdall and upstream components, which may result in authorization bypass. This issue has been patched in version 0.17.14.
- How severe is CVE-2026-42272?
- CVE-2026-42272 has a CVSS 4.0 base score of 7.8, rated high severity.
- Is CVE-2026-42272 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (32nd percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-42272?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2026-42272 have an EU (EUVD) identifier?
- Yes. CVE-2026-42272 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-28508.
- When was CVE-2026-42272 published?
- CVE-2026-42272 was published on 2026-05-08 and last updated on 2026-06-17.
References
- https://github.com/dadrus/heimdall/commit/8b0de6aba23a047cfee3081df878271bb17f4351
- https://github.com/dadrus/heimdall/pull/3207
- https://github.com/dadrus/heimdall/releases/tag/v0.17.14
- https://github.com/dadrus/heimdall/security/advisories/GHSA-43jv-5j4x-qv67
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