CVE-2026-88008: Traefik is an open source HTTP reverse proxy and load balancer

This month

CRITICAL 9.1REMOTEUPGRADE

CVE-2026-88008 is a critical-severity flaw (CVSS 9.1) 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 2.11.26 until 2.11.57 and 3.7.13, Traefik forwards a client-supplied Connection header requesting Upgrade, the Upgrade: h2c token, and HTTP2-Settings to a shared backend. If the backend accepts h2c and returns 101 Switching Protocols, Traefik enters a raw tunnel and no longer applies routers, BasicAuth, ForwardAuth, IPAllowList, RateLimit, access logging, metrics, or tracing to

Why this priority

Critical severity
Remotely exploitable, no login, no user action

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 58%)
CISA exploited list	No
Weakness	CWE-444, CWE-863
Published	2026-09-10
Last modified	2026-09-14

Publisher (CNA): GitHub, Inc. · Vendor: traefik

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

Am I affected?

Timeline

2026-09-10 15:17 UTCPublished CVE record published
2026-09-14 19:59 UTCUpdated Record last modified

traefik traefik UPGRADE

Affected: >= 2.11.26 and < 2.11.57 · >= 3.4.2 and < 3.7.13

Fixed in: 2.11.57, 3.7.13

Safe to downgrade to: a release before 2.11.26

1. Check installed version

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

2. UPGRADE to 2.11.57 (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 2.11.26 (Debian / Ubuntu)

apt-cache madison traefik sudo apt install traefik=<VERSION_BEFORE_2.11.26> 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_2.11.26> 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-2026-88008?

traefik: upgrade to 2.11.57, 3.7.13. Exact commands for each OS are on this page.

Is CVE-2026-88008 being exploited?

CVE-2026-88008 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-2026-88008 affect?

CVE-2026-88008 affects traefik. Severity is critical (CVSS 9.1). Traefik is an open source HTTP reverse proxy and load balancer. From 2.11.26 until 2.11.57 and 3.7.13, Traefik forwards a client-supplied Connection header requesting Upgrade, the Upgrade: h2c token, and HTTP2-Settings to a shared backend.

How urgent is CVE-2026-88008?

Priority 47/100. Critical severity; Remotely exploitable, no login, no user action

Software pages

Traefik vulnerabilities

Related CVEs

CVE-2026-65600 MEDIUM 5.3 UPGRADE Traefik versions <= v2.11.51, >= v3.6.0 <= v3.6.22, and >= v3.7.0 <= v3.7.6 contain an authentication bypass v
CVE-2026-112778 HIGH 8.8 UPGRADE Traefik before 2.11.46, 3.x before 3.6.17, and 3.7.0 lack namespace validation for Ingress and Service annotat
CVE-2026-88879 HIGH 8.2 UPGRADE Traefik is an HTTP reverse proxy and load balancer
CVE-2026-88878 MEDIUM 5.3 UPGRADE Traefik is an HTTP reverse proxy and load balancer
CVE-2026-88877 CRITICAL 9.8 UPGRADE Traefik is a HTTP reverse proxy and load balancer

References

← Back to latest CVEs