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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.9 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS

• CVE-2026-69201: 0.76% estimated exploitation activity in the next 30 days; percentile 55.27 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

The static content handlers ResourceService and WebjarService URL decode each path segment and then reject only segments that are exactly "", ".", or "..". A percent-encoded separator (%2F) lets an attacker smuggle a ../ segment past that filter and escape the configured base, reading resources that should not be public. On Windows, a similar attack exists with (%5C). Impact Disclosure of classpath or webjar resources outside the configured base. Preconditions - Application uses ResourceService (with a non-root base path) or WebjarService - At least one classpath entry is served from a directory (e.g. sbt run, exploded .war) - Backend forwards %2F/%5C without normalizing (e.g., Ember, Blaze) Fixes The patch rejects any decoded path segment containing / (%2F) or \ (%5C) with a 400 Bad Request in ResourceService and WebjarService. FileService was not exploitable, but the same guards are applied for consistency and to remove its reliance on path normalization. Workarounds - Deploy as a…

Published by the source

15 Sep 2026, 20:01 UTC

Last modified by the source

15 Sep 2026, 20:15 UTC

Source last checked

26 Oct 2026, 16:55 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-crq5-92j2-j7wv

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-crq5-92j2-j7wv

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# Patch Next advisory brief: CVE-2026-69201

Advisory: Http4s: ResourceService and Webjar Service path escape via percent-encoded separators
IDs: CVE-2026-69201, GHSA-crq5-92j2-j7wv
Record: https://patchnext.com/advisories/cve-2026-69201 (revision 2, source checked 26 Oct 2026, 16:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: org.http4s:http4s-server_3 1.0.0-M47, 0.23.35; org.http4s:http4s-server_2.13 1.0.0-M47, 0.23.35; org.http4s:http4s-server_2.12 0.23.35. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.http4s:http4s-server_3: affected <= 0.23.34; >= 1.0.0-M1, <= 1.0.0-M46; fixed in 0.23.35, 1.0.0-M47
- Maven org.http4s:http4s-server_2.13: affected <= 0.23.34; >= 1.0.0-M1, <= 1.0.0-M46; fixed in 0.23.35, 1.0.0-M47
- Maven org.http4s:http4s-server_2.12: affected <= 0.23.34; fixed in 0.23.35

## Suggested inspection (read-only)
- Maven org.http4s:http4s-server_3: check the installed version with your package manager.
- Maven org.http4s:http4s-server_2.13: check the installed version with your package manager.
- Maven org.http4s:http4s-server_2.12: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on org.http4s:http4s-server_3, org.http4s:http4s-server_2.13, org.http4s:http4s-server_2.12.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-crq5-92j2-j7wv (OSV record GHSA-crq5-92j2-j7wv lists affected ranges: Maven org.http4s:http4s-server_2.12 >=0 =0 =1.0.0-M1 =0 =1.0.0-M1 <1.0.0-M47 (fixed))
- Verified: https://github.com/advisories/GHSA-crq5-92j2-j7wv (GitHub-reviewed advisory GHSA-crq5-92j2-j7wv lists affected ranges: Maven org.http4s:http4s-server_2.12 >=0 =0 =1.0.0-M1 =0 =1.0.0-M1 <=1.0.0-M46)

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