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CVE-2026-88004: Traefik is an open source HTTP reverse proxy and load balancer

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HIGH 7.4REMOTEUPGRADE

CVE-2026-88004 is a high-severity flaw (CVSS 7.4) affecting traefik. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Traefik is an open source HTTP reverse proxy and load balancer. From 3.2.0 until 3.7.13, Traefik entrypoint defenses aliasHeadersStrategy, underscoreHeadersStrategy, and forwardedHeaders inspect req.Header but not req.Trailer, allowing an unauthenticated client to submit an aliasing or trusted header name in an HTTP/1.1 chunked trailer or an HTTP/2 trailer. When the retry or buffering middleware reads the body before the reverse proxy clones the

Why this priority

  • High severity
  • Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score7.4 (High)
Attack vectorNetwork (remote)
Attack complexityHigh
Privileges neededNone
User interactionNone
EPSS exploit chance0.5% (top 61%)
CISA exploited listNo
WeaknessCWE-436, CWE-807
Published2026-09-10
Last modified2026-09-14
Publisher (CNA): GitHub, Inc. · Vendor: traefik

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Last updated 2026-09-14 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

traefik traefik UPGRADE
Affected: >= 3.2.0 and < 3.7.13
Fixed in: 3.7.13
Safe to downgrade to: a release before 3.2.0
1. Check installed version
apt-cache policy traefik || rpm -q traefik || traefik --version
2. UPGRADE to 3.7.13 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade traefik
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade traefik
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 3.2.0 (Debian / Ubuntu)
apt-cache madison traefik sudo apt install traefik=<VERSION_BEFORE_3.2.0> sudo apt-mark hold traefik
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list traefik sudo dnf downgrade traefik-<VERSION_BEFORE_3.2.0> sudo dnf versionlock add traefik
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-2026-88004?

traefik: upgrade to 3.7.13. Exact commands for each OS are on this page.

Is CVE-2026-88004 being exploited?

CVE-2026-88004 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-2026-88004 affect?

CVE-2026-88004 affects traefik. Severity is high (CVSS 7.4). Traefik is an open source HTTP reverse proxy and load balancer. From 3.2.0 until 3.7.13, Traefik entrypoint defenses aliasHeadersStrategy, underscoreHeadersStrategy, and forwardedHeaders inspect req.Header but not req.Trailer, allowing an u

How urgent is CVE-2026-88004?

Priority 41/100. High severity; Remotely exploitable, no login, no user action

Software pages

Traefik vulnerabilities

Related CVEs

References

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