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Advisory record · GHSA-hqxw-mm44-gc4r

Istio Fragments in Path May Lead to Authorization Policy Bypass

CVSS 8.1 HighEPSS 0.012 · 67th percentile

Published by the GitHub Advisory Database at 30 Aug 2021, 16:16 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
istio.io/istioGo<1.9.8 || >=1.10.0, <1.10.4 || >=1.11.0, <1.11.11.9.8, 1.10.4, 1.11.1
Identifiers
GHSA-hqxw-mm44-gc4r · CVE-2021-39156
Weakness (CWE)
CWE-706 · CWE-863
Tags
Published
30 Aug 2021
Updated
10 Sept 2026

Machine-written summary

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

Istio versions below 1.9.8, from 1.10.0 up to 1.10.4, and from 1.11.0 up to 1.11.1 are vulnerable. A remote attacker can send an HTTP request with a fragment in the path to bypass Istio's URI path-based authorization policies. Upgrade to Istio 1.9.8, 1.10.4, or 1.11.1 or later; a Lua filter that normalizes the request path is a documented workaround.

Written 6 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
8.1 High 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.012, the 67th percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:44 UTC First seen by agentprime
  2. 31 Oct 2026, 14:44 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.