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OpenAdvisories
Medium · 5.9 CVE-2026-69201 EUVD-2026-79177GHSA-crq5-92j2-j7wv

Http4s: ResourceService and Webjar Service path escape via percent-encoded separators

Published Sep 15, 2026 · Updated Sep 15, 2026 · Assigned by GitHub_M

Description

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, ResourceService and WebjarService decode each URL path segment but reject only segments exactly equal to an empty string, a dot, or two dots. A request containing percent-encoded slash or backslash separators can turn an accepted segment into a parent-directory traversal after decoding, allowing access to classpath or WebJar resources outside the configured base when a directory-backed classpath is served and the backend preserves the encoded separator. The patch rejects decoded segments containing slash or backslash in ResourceService and WebjarService, and applies the same guard to the non-exploitable FileService for consistency. This issue is fixed in versions 0.23.35 and 1.0.0-M47.

Affected products

VendorProductAffectedFixed
http4s http4s < 0.23.35, >= 1.0.0-M1, < 1.0.0-M47 —

Affected packages

EcosystemPackageAffectedFixedRecord
Maven org.http4s:http4s-server_2.12 < 0.23.35 0.23.35 GHSA-crq5-92j2-j7wv
Maven org.http4s:http4s-server_2.13 < 0.23.35 0.23.35 GHSA-crq5-92j2-j7wv
Maven org.http4s:http4s-server_2.13 >= 1.0.0-M1, < 1.0.0-M47 1.0.0-M47 GHSA-crq5-92j2-j7wv
Maven org.http4s:http4s-server_3 < 0.23.35 0.23.35 GHSA-crq5-92j2-j7wv
Maven org.http4s:http4s-server_3 >= 1.0.0-M1, < 1.0.0-M47 1.0.0-M47 GHSA-crq5-92j2-j7wv

References