What is CVE-2026-39998?

CVE-2026-39998 is a high-severity vulnerability in Apache Apisix, classified under Improper Input Validation. CVSS score: 8.8/10. Published 2026-06-19.

How severe is CVE-2026-39998?

High severity. CVSS v3 base score is 8.8 out of 10.

Improper input validation in Apache Apisix

CVE-2026-39998

Improper Input Validation vulnerability in Apache APISIX. The attacker can take advantage of certain configuration in forward-auth plugin to spoof identity headers. This issue affects Apache APISIX: from 2.12.0 through 3.16.0. Users are recommended to upgrade to version 3.17.0, which fixes the issue.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

Published 2026-06-19 · last modified 2026-06-23.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.007 (50.3th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 50th percentile — 50.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000

Affected products

Apache Apisix
Apache Software Foundation Apisix — versions 2.12.0

Weakness classification (CWE)

CWE-20 — Improper Input Validation

References

lists.apache.org/thread/vgkvy396010d7g6m0jrn4d3hjf2svlvv (vendor-advisory, Mailing List, Vendor Advisory)
af854a3a-2127-422b-91ae-364da2661108 (Third Party Advisory)

Frequently asked questions

What is CVE-2026-39998?: CVE-2026-39998 is a high-severity vulnerability in Apache Apisix, classified under Improper Input Validation. CVSS score: 8.8/10. Published 2026-06-19.
How severe is CVE-2026-39998?: High severity. CVSS v3 base score is 8.8 out of 10.