CVE-2026-42272

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.

Is your site exposed to CVE-2026-42272?

Run a free security scan — no signup, results in seconds.

EPSS — Exploit Prediction

0.0002

Probability of exploitation

0.05%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-178 CWE-178

CWE-436 CWE-436

References

Other 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

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 do I check if I'm vulnerable to CVE-2026-42272? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-84303

gRPC-Go is the Go language implementation of gRPC. Prior to 1.83.1, the xDS RBAC HTTP filter in internal/xds/httpfilter/rbac/rbac.go does not …

CVE-2026-73270

Improper Handling of Case Sensitivity vulnerability in Erlang/OTP inets httpd allows a remote unauthenticated attacker to read files inside a …

CVE-2026-83612

xmldom is a pure JavaScript W3C standard-based (XML DOM Level 2 Core) DOMParser and XMLSerializer module. From 0.9.0-beta.1 until 0.9.12, …

CVE-2026-105570

Docker Sandboxes compared OAuth token-endpoint hostnames case-sensitively when deciding whether to mask managed credential responses, while request routing treated DNS …

CVE-2026-66883

Improper Handling of Case Sensitivity vulnerability in Erlang Ecosystem Foundation oidcc_plug (Oidcc.Plug.Authorize module) renders the user agent session binding inert, …

CVE-2026-62673

Grav is a file-based Web platform. Prior to 2.0.4, the Grav .htaccess and webserver-configs/htaccess.txt security rules omit the Apache [NC] …