CVE-2026-85595: Traefik versions before v2.11.55 and versions v3.0.0 through v3.7.10 contain an authentication bypass vulnerab

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CRITICAL 9.8REMOTEUPGRADE

CVE-2026-85595 is a critical-severity flaw (CVSS 9.8) affecting traefik. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Traefik versions before v2.11.55 and versions v3.0.0 through v3.7.10 contain an authentication bypass vulnerability in the digestAuth middleware where unknown usernames receive an empty secret instead of rejection. Attackers can compute a valid digest response using the empty secret and arbitrary credentials to bypass authentication on any digestAuth-protected route without a valid username or password.

Why this priority

Critical severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.7% (top 47%)
CISA exploited list	No
Weakness	CWE-287
Published	2026-09-04
Last modified	2026-10-08

Publisher (CNA): VulnCheck · Vendor: traefik

Last updated 2026-10-08 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-04 12:17 UTCPublished CVE record published
2026-10-08 16:17 UTCUpdated Record last modified

traefik traefik UPGRADE

Affected: < 2.11.55 · >= 3.0.0 and < 3.7.11

Fixed in: 2.11.55, 3.7.11

Safe to downgrade to: a release before 3.0.0

1. Check installed version

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

2. UPGRADE to 2.11.55 (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 3.0.0 (Debian / Ubuntu)

apt-cache madison traefik sudo apt install traefik=<VERSION_BEFORE_3.0.0> 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_3.0.0> 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.

Exact fixes by distribution

Fedora 46 · ddnet · FIXED · 20.2-1.fc46 · FEDORA-2026-6991b4ab14 · source

sudo dnf upgrade --advisory=FEDORA-2026-6991b4ab14

Fedora ELN · libplacebo · FIXED · 7.360.1-5.eln159 · FEDORA-2026-92226f221e · source

sudo dnf upgrade --advisory=FEDORA-2026-92226f221e

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

GitHub PoC: Boreas37/CVE-2026-85595-PoC (0 stars)
Write-up: github.com/traefik/traefik/security/advisories/GHSA-5w68-77r2-r64c

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-2026-85595?

traefik: upgrade to 2.11.55, 3.7.11. Exact commands for each OS are on this page.

Is CVE-2026-85595 being exploited?

CVE-2026-85595 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-2026-85595 affect?

CVE-2026-85595 affects traefik. Severity is critical (CVSS 9.8). Traefik versions before v2.11.55 and versions v3.0.0 through v3.7.10 contain an authentication bypass vulnerability in the digestAuth middleware where unknown usernames receive an empty secret instead of rejection. Attackers can compute a v

How urgent is CVE-2026-85595?

Priority 57/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

Traefik vulnerabilities

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References

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