CVE-2026-119574: Traefik from 3.2.0 before 3.7.15 contains a data race in the experimental FastProxy that allows unauthenticate

Routine

MEDIUM 5.9REMOTEUPGRADE

CVE-2026-119574 is a medium-severity flaw (CVSS 5.9) affecting traefik. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Traefik from 3.2.0 before 3.7.15 contains a data race in the experimental FastProxy that allows unauthenticated attackers to crash the process by abusing HTTP/1 protocol upgrades. Attackers can repeatedly open and abort upgraded connections such as WebSocket, corrupting the unsynchronized shared bufio.Reader and triggering an unrecovered panic that terminates Traefik.

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.9 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 79%)
CISA exploited list	No
Weakness	CWE-567
Published	2026-10-30
Last modified	2026-11-03

Publisher (CNA): VulnCheck · Vendor: traefik

Last updated 2026-11-03 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-10-30 14:16 UTCPublished CVE record published
2026-11-03 14:04 UTCUpdated Record last modified

traefik traefik UPGRADE

Affected: >= 3.2.0 and < 3.7.15

Fixed in: 3.7.15

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 3.7.15 (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.

Advisories and coverage

Research and news

VulDB Recent Entries: CVE-2026-119574 | Traefik Labs up to 3.7.14 FastProxy race condition 2026-10-30

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-2026-119574?

traefik: upgrade to 3.7.15. Exact commands for each OS are on this page.

Is CVE-2026-119574 being exploited?

CVE-2026-119574 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-2026-119574 affect?

CVE-2026-119574 affects traefik. Severity is medium (CVSS 5.9). Traefik from 3.2.0 before 3.7.15 contains a data race in the experimental FastProxy that allows unauthenticated attackers to crash the process by abusing HTTP/1 protocol upgrades. Attackers can repeatedly open and abort upgraded connections

How urgent is CVE-2026-119574?

Priority 31/100. Remotely exploitable, no login, no user action

Software pages

Traefik vulnerabilities

Related CVEs

CVE-2026-119573 MEDIUM 4.4 UPGRADE Traefik 3.7.11 before 3.7.15 contains an authorization bypass in the Kubernetes Ingress NGINX provider that sk
CVE-2026-114656 HIGH 7.5 UPGRADE Traefik before 2.11.58 and 3.7.13 contains an authentication bypass vulnerability that allows unauthenticated
CVE-2026-88010 MEDIUM 5.3 UPGRADE Traefik is an open source HTTP reverse proxy and load balancer
CVE-2026-114641 LOW 3.7 UPGRADE Traefik 2.11.x before 2.11.58 and 3.x before 3.7.14 contains a race condition in NTLM and Kerberos (Negotiate)
CVE-2026-114637 HIGH 8.7 UPGRADE Traefik from v3.2.0 before v3.7.14 contains an authentication bypass vulnerability in the experimental FastPro

References

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