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VulnerabilityPublished

CVE-2026-41263: traefik · Timing Side Channel

Affects traefikSource GCVE Database

0

Not known to be exploited · CVSS 6.3 Medium · fixed in 3.7.0-rc.2 : update traefik when convenient.

Data as of 27 Oct 2026, 00:39 UTC

CVSS 4.0 base score
6.3Medium
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 3.7.0-rc.2, 3.6.14, 2.11.43
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 30 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade traefik to 3.7.0-rc.2, 3.6.14 or 2.11.43.

Affected software

ProductAffectedFixed in
traefik traefikAffected
  • <2.11.43
  • >=3.0.0-beta1 <3.6.14
  • >=3.7.0-ea.1 <3.7.0-rc.2
Fixed in
  • 2.11.43
  • 3.6.14
  • 3.7.0-rc.2

AI-suggested

Upgrade Traefik to version 2.11.43, 3.6.14, or 3.7.0-rc.2 or later to apply the official fix for this timing side-channel vulnerability. No other mitigation is required as the issue is resolved in these versions.

Description

A timing side-channel vulnerability in Traefik's BasicAuth middleware prior to versions 2.11.43, 3.6.14, and 3.7.0-rc.2 allows attackers to enumerate valid usernames by measuring authentication response times. The issue arises because a variable intended for a constant-time fallback secret is empty, causing the comparison to short-circuit quickly and reveal timing differences. This vulnerability has been patched in the specified versions.

References

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