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UK Cyber Defence
VulnerabilityAnalyzed

CVE-2026-39998

Improper Input Validation vulnerability in Apache APISIX.

MEDIUM 5.8EPSS 0.68%

Does this matter?

Lower severity and a low EPSS score (0.68%). Track it; it rarely justifies an emergency change on its own.

Description

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.

CVSS 4.0
5.8 MEDIUMCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS
0.68% probability · 50th percentile
CISA KEV
Not listed
Weakness
CWE-20
Affected
apache/apisix
Source
security@apache.org

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.