CVE-2026-31908: Header injection vulnerability in Apache APISIX. The attacker can take advantage of certain configuration in

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CRITICAL 9.1REMOTEWATCHLISTUPGRADE

CVE-2026-31908 is a critical-severity flaw (CVSS 9.1) affecting apisix. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Critical severity
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.1 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 56%)
CISA exploited list	No
Weakness	CWE-75
Published	2026-04-14
Last modified	2026-10-26

Publisher (CNA): Apache Software Foundation · Vendor: apache

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-14 09:16 UTCPublished CVE record published
2026-10-26 21:10 UTCUpdated Record last modified

apache apisix UPGRADE

Affected: >= 2.12.0 and < 3.16.0

Fixed in: 3.16.0

Safe to downgrade to: a release before 2.12.0

1. Check installed version

apt-cache policy apisix || rpm -q apisix || apisix --version

2. UPGRADE to 3.16.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade apisix

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade apisix

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2.12.0 (Debian / Ubuntu)

apt-cache madison apisix sudo apt install apisix=<VERSION_BEFORE_2.12.0> sudo apt-mark hold apisix

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list apisix sudo dnf downgrade apisix-<VERSION_BEFORE_2.12.0> sudo dnf versionlock add apisix

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-31908?

apisix: upgrade to 3.16.0. Exact commands for each OS are on this page.

Is CVE-2026-31908 being exploited?

CVE-2026-31908 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-31908 affect?

CVE-2026-31908 affects apisix. Severity is critical (CVSS 9.1). 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 recommen

How urgent is CVE-2026-31908?

Priority 53/100. Critical severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Apache APISIX vulnerabilities

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References

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