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Advisory record · GHSA-crq5-92j2-j7wv

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

CVSS 5.9 MediumEPSS 0.0076 · 55th percentile

Published by the GitHub Advisory Database at 15 Sept 2026, 20:01 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
org.http4s:http4s-server_2.12Maven<0.23.350.23.35
org.http4s:http4s-server_2.13Maven<0.23.35 || >=1.0.0-M1, <1.0.0-M470.23.35, 1.0.0-M47
org.http4s:http4s-server_3Maven<0.23.35 || >=1.0.0-M1, <1.0.0-M470.23.35, 1.0.0-M47
Identifiers
GHSA-crq5-92j2-j7wv · CVE-2026-69201
Weakness (CWE)
CWE-22
Tags
Published
15 Sept 2026
Updated
15 Sept 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Http4s http4s-server versions before 0.23.35 and from 1.0.0-M1 before 1.0.0-M47 are vulnerable, with the fix in 0.23.35 and 1.0.0-M47. ResourceService and WebjarService decode percent-encoded path separators (%2F, and %5C on Windows) after their filter, so a remote attacker can escape the configured base and read resources that should not be public. Upgrade to 0.23.35 or 1.0.0-M47 or later; alternatively, deploy as a fat jar with no filesystem directories on the classpath, or place a proxy in front that rejects or normalizes %2F and %5C.

Written 2 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
5.9 Medium 3.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0076, the 55th percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:16 UTC First seen by agentprime
  2. 31 Oct 2026, 14:16 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.