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Fencer Vulns
medium 5.9

CVE-2026-22045 json

Traefik's ACME TLS-ALPN fast path lacks timeouts and close on handshake stall

published 2026-01-15 9 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-2949 , GHSA-cwjm-3f7h-9hwq , GO-2026-4322

cvss
5.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 27%
public exploits
0
none known

Summary

Traefik is an HTTP reverse proxy and load balancer. Prior to 2.11.35 and 3.6.7, there is a potential vulnerability in Traefik ACME TLS certificates' automatic generation: the ACME TLS-ALPN fast path can allow unauthenticated clients to tie up go routines and file descriptors indefinitely when the ACME TLS challenge is enabled. A malicious client can open many connections, send a minimal ClientHello with acme-tls/1, then stop responding, leading to denial of service of the entry point. The vulnerability is fixed in 2.11.35 and 3.6.7.

Patch / fix

  • go github.com/traefik/traefik/v3 3.6.7
  • go github.com/traefik/traefik/v2 2.11.35
  • traefik traefik 2.11.35, 3.6.7
  • govulncheck-vulndb openSUSE Leap 15.6 0.0.20260123T022811-150000.1.140.1

suse advisories SUSE-SU-2026:0292-1

  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1
  • traefik openSUSE Tumbleweed 3.6.7-1.1
  • traefik2 openSUSE Tumbleweed 2.11.35-1.1

opensuse advisories openSUSE-SU-2026:21483-1openSUSE-SU-2026:10142-1openSUSE-SU-2026:10143-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-22045 updated cvss 5.9

traefik: Traefik: Denial of Service via ACME TLS-ALPN fast path resource exhaustion

  • Red Hat OpenShift Dev Spaces 3.27 devspaces 1774227265
    fixed: vendor fix RHSA-2026:6192
  • Red Hat OpenShift Dev Spaces 3.27 devspaces 1773775028, devspaces 1773775064, devspaces 1773775544, devspaces 1774070844, devspaces 1774143680, devspaces 1774155063, +9 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
9 mo ago

Exploit prediction

0.34% chance of exploitation in the next 30 days, higher than 27% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
go github.com/traefik/traefik/v3
<3.6.7
3.6.7
go github.com/traefik/traefik/v2
<2.11.35
2.11.35
go github.com/traefik/traefik
all versions
 no fix listed

Affected products

  • traefik traefik

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.