CVE-2026-31908 | Apache APISIX: forward auth plugin allows header injection

Header injection vulnerability in Apache APISIX. The attacker can take advantage of certain configuration in forward-auth plugin to inject malicious headers. This issue affects Apache APISIX: from 2.12.0 through 3.15.0. Users are recommended to upgrade to version 3.16.0, which fixes the issue.

Published: 2026-04-14 Last update: 2026-04-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-31908 is rated Moderate Risk (41/100): CVSS Critical severity, with low exploitation likelihood (EPSS 0.04%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-31908

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-22 0.09% 0.04% -0.05%
2 2026-04-18 0.03% 0.09% +0.06%
3 2026-04-14 — 0.03% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-31908

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.1 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 5.2 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2026-31908

GitHub Security Advisory for CVE-2026-31908

GHSA-jv22-34xc-w9x6 · Severity: critical — Header injection vulnerability in Apache APISIX. The attacker can take advantage of certain...

Affected software / configurations for CVE-2026-31908

Vendor Product Version Raw CPE
apache apisix >= 2.12.0, < 3.16.0 cpe:2.3:a:apache:apisix:*:*:*:*:*:*:*:*

References for CVE-2026-31908

cvelogic Threat Intelligence