How severe is CVE-2025-66490?

CVE-2025-66490 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2025-66490 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (26th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-66490?

CVE-2025-66490 affects Traefik. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-66490?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2025-66490 have an EU (EUVD) identifier?

Yes. CVE-2025-66490 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201731.

When was CVE-2025-66490 published?

CVE-2025-66490 was published on 2025-12-09 and last updated on 2026-06-17.

CVE-2025-66490

CVE-2025-66490 is a medium-severity vulnerability in Traefik with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-436.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v4: 6.9
EPSS exploit prediction: 0% (26th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-201731
Weakness: CWE-436
Affected product: Traefik
Published: 2025-12-09
Last modified: 2026-06-17

Description

Traefik is an HTTP reverse proxy and load balancer. For versions prior to 2.11.32 and 2.11.31 through 3.6.2, requests using PathPrefix, Path or PathRegex matchers can bypass path normalization. When Traefik uses path-based routing, requests containing URL-encoded restricted characters (/, \, Null, ;, ?, #) can bypass the middleware chain and reach unintended backends. For example, a request to http://mydomain.example.com/admin%2F could reach service-a without triggering my-security-middleware, bypassing security controls for the /admin/ path. This issue is fixed in versions 2.11.32 and 3.6.3.

Frequently asked questions

What is CVE-2025-66490?: Traefik is an HTTP reverse proxy and load balancer. For versions prior to 2.11.32 and 2.11.31 through 3.6.2, requests using PathPrefix, Path or PathRegex matchers can bypass path normalization. When Traefik uses path-based routing, requests containing URL-encoded restricted characters (/, \, Null, ;, ?, #) can bypass the middleware chain and reach unintended backends. For example, a request to http://mydomain.example.com/admin%2F could reach service-a without triggering my-security-middleware, bypassing security controls for the /admin/ path. This issue is fixed in versions 2.11.32 and 3.6.3.
How severe is CVE-2025-66490?: CVE-2025-66490 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2025-66490 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (26th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-66490?: CVE-2025-66490 affects Traefik. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-66490?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-66490 have an EU (EUVD) identifier?: Yes. CVE-2025-66490 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201731.
When was CVE-2025-66490 published?: CVE-2025-66490 was published on 2025-12-09 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*

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