CVE-2026-65600: github.com/traefik/traefik/v2 (Go)

Should you act?

Normal patch cycle

No exploitation signal; fix it in your next routine update if you are affected. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
EPSS 0.6%, percentile 49: FIRST’s model estimates a 0.6% chance of exploitation activity in the next 30 days, higher than 49% of all scored CVEs (low). EPSS is a probability, not a verdict.
Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
Only applies if your dependency tree includes github.com/traefik/traefik/v2 (Go) <= 2.11.51, fixed in 2.11.52; github.com/traefik/traefik/v3 (Go) <= 3.6.22, fixed in 3.6.23; github.com/traefik/traefik/v3 (Go) >= 3.7.0, <= 3.7.6, fixed in 3.7.7; github.com/traefik/traefik (Go) <= 1.7.34, no fixed version listed. Check your lockfile, including transitive dependencies.

What it is

Traefik versions = v3.6.0 = v3.7.0

From the GitHub advisory

Summary

There is a critical authentication-bypass vulnerability in Traefik's ReplacePathRegex middleware. When it is configured with a regular expression that captures user-controlled path segments without a mandatory separator (for example regex: "^/api(.)", replacement: "/$1"), a crafted request can produce an un-normalized replacement path such as /../admin, which Traefik forwarded to the backend without validation. A backend that normalizes the path may resolve it to a protected route, letting an unauthenticated attacker reach resources located behind authentication middleware. This is the same class of issue that was fixed for StripPrefix in CVE-2026-48020; that post-replacement normalization check had not been applied to ReplacePathRegex. The fix rejects any request whose replaced path does not match its normalized form.

Patches

- https://github.com/traefik/traefik/releases/tag/v2.11.52 - https://github.com/traefik/traefik/releases/tag/v3.6.23 - https://github.com/traefik/traefik/releases/tag/v3.7.7

For more information

Weakness type: CWE-22.

Product: github.com/traefik/traefik/v2 (Go) · Assigned by: VulnCheck · Published: 2026-07-22

Affected and fixed versions

Ecosystem	Package	Vulnerable	First fixed
Go	`github.com/traefik/traefik/v2`	<= 2.11.51	2.11.52
Go	`github.com/traefik/traefik/v3`	<= 3.6.22	3.6.23
Go	`github.com/traefik/traefik/v3`	>= 3.7.0, <= 3.7.6	3.7.7
Go	`github.com/traefik/traefik`	<= 1.7.34	none listed

Vendor	Product	Affected versions (per CVE record)
traefik	traefik	< 2.11.52
traefik	traefik	3.6.0 < 3.6.23
traefik	traefik	3.7.0 < 3.7.7

Severity scores

Scored by	CVSS	Score	Vector
VulnCheck	4.0	7.8 High	`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N`
GitHub	3.1	9.1	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`

Attack vector: network (remotely reachable)
Attack complexity: low
Attack requirements: none
Privileges required: none (no login)
User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
CISA SSVC assessment: exploitation none, automatable yes, technical impact partial.
FIRST EPSS (model of 2026-10-21): 0.62% probability of exploitation activity in the next 30 days; percentile 49.

Timeline

2026-07-22 — CVE record published by VulnCheck
2026-08-06 — GitHub-reviewed advisory GHSA-cxjq-mrr5-89rv published (critical)
2026-10-08 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.