CVE-2026-26999
published 2026-03-05CVE-2026-26999: Traefik is an HTTP reverse proxy and load balancer. Prior to versions 2.11.38 and 3.6.9, there is a potential vulnerability in Traefik managing TLS handshake…
PriorityP346high7.5CVSS 3.1
AVNACLPRNUINSUCNINAH
EPSS
0.54%
41.2th percentile
Traefik is an HTTP reverse proxy and load balancer. Prior to versions 2.11.38 and 3.6.9, there is a potential vulnerability in Traefik managing TLS handshake on TCP routers. When Traefik processes a TLS connection on a TCP router, the read deadline used to bound protocol sniffing is cleared before the TLS handshake is completed. When a TLS handshake read error occurs, the code attempts a second handshake with different connection parameters, silently ignoring the initial error. A remote unauthenticated client can exploit this by sending an incomplete TLS record and stopping further data transmission, causing the TLS handshake to stall indefinitely and holding connections open. By opening many such stalled connections in parallel, an attacker can exhaust file descriptors and goroutines, degrading availability of all services on the affected entrypoint. This issue has been patched in versions 2.11.38 and 3.6.9.
Affected
5 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| github.com | traefik_traefik_v2 | >= 0 < 2.11.38 | 2.11.38 |
| github.com | traefik_traefik_v3 | >= 0 < 3.6.9 | 3.6.9 |
| traefik | traefik | < 3.6.9 | 3.6.9 |
| traefik | traefik | < 2.11.38 | 2.11.38 |
| traefik | traefik | >= 3.0.0 < 3.6.9 | 3.6.9 |
CVSS provenance
nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
vendor_redhat7.5HIGH
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VulDB
Traefik up to 2.11.37/3.6.8 TLS Connection resource consumption (Nessus ID 318671)
vuldb·2026-06-05·CVSS 7.5
CVE-2026-26999 [HIGH] Traefik up to 2.11.37/3.6.8 TLS Connection resource consumption (Nessus ID 318671)
A vulnerability categorized as problematic has been discovered in Traefik up to 2.11.37/3.6.8. Affected is an unknown function of the component TLS Connection Handler. Such manipulation leads to resource consumption.
This vulnerability is listed as CVE-2026-26999. The attack may be performed from remote. There is no available exploit.
It is advisable to upgrade the affected component.
OSV
Traefik: tcp router clears read deadlines before tls forwarding, enabling stalled handshakes (Slowloris DOS) in github.com/traefik/traefik
osv·2026-03-10
CVE-2026-26999 Traefik: tcp router clears read deadlines before tls forwarding, enabling stalled handshakes (Slowloris DOS) in github.com/traefik/traefik
Traefik: tcp router clears read deadlines before tls forwarding, enabling stalled handshakes (Slowloris DOS) in github.com/traefik/traefik
Traefik: tcp router clears read deadlines before tls forwarding, enabling stalled handshakes (Slowloris DOS) in github.com/traefik/traefik
OSV
Traefik: tcp router clears read deadlines before tls forwarding, enabling stalled handshakes (Slowloris DOS)
osv·2026-03-04
CVE-2026-26999 [HIGH] Traefik: tcp router clears read deadlines before tls forwarding, enabling stalled handshakes (Slowloris DOS)
Traefik: tcp router clears read deadlines before tls forwarding, enabling stalled handshakes (Slowloris DOS)
## Impact
There is a potential vulnerability in Traefik managing TLS handshake on TCP routers.
When Traefik processes a TLS connection on a TCP router, the read deadline used to bound protocol sniffing is cleared before the TLS handshake is completed. When a TLS handshake read error occurs, the code attempts a second handshake with different connection parameters, silently ignoring the initial error. A remote unauthenticated client can exploit this by sending an incomplete TLS record and stopping further data transmission, causing the TLS handshake to stall indefinitely and holding connections open.
By opening many such stalled connections in parallel, an attacker can exhaust fi
GHSA
Traefik: tcp router clears read deadlines before tls forwarding, enabling stalled handshakes (Slowloris DOS)
ghsa·2026-03-04
CVE-2026-26999 [HIGH] CWE-400 Traefik: tcp router clears read deadlines before tls forwarding, enabling stalled handshakes (Slowloris DOS)
Traefik: tcp router clears read deadlines before tls forwarding, enabling stalled handshakes (Slowloris DOS)
## Impact
There is a potential vulnerability in Traefik managing TLS handshake on TCP routers.
When Traefik processes a TLS connection on a TCP router, the read deadline used to bound protocol sniffing is cleared before the TLS handshake is completed. When a TLS handshake read error occurs, the code attempts a second handshake with different connection parameters, silently ignoring the initial error. A remote unauthenticated client can exploit this by sending an incomplete TLS record and stopping further data transmission, causing the TLS handshake to stall indefinitely and holding connections open.
By opening many such stalled connections in parallel, an attacker can exhaust fi
Red Hat
github.com/traefik/traefik: Traefik: Denial of Service due to incomplete TLS handshake
vendor_redhat·2026-03-05·CVSS 7.5
CVE-2026-26999 [HIGH] CWE-772 github.com/traefik/traefik: Traefik: Denial of Service due to incomplete TLS handshake
github.com/traefik/traefik: Traefik: Denial of Service due to incomplete TLS handshake
Traefik is an HTTP reverse proxy and load balancer. Prior to versions 2.11.38 and 3.6.9, there is a potential vulnerability in Traefik managing TLS handshake on TCP routers. When Traefik processes a TLS connection on a TCP router, the read deadline used to bound protocol sniffing is cleared before the TLS handshake is completed. When a TLS handshake read error occurs, the code attempts a second handshake with different connection parameters, silently ignoring the initial error. A remote unauthenticated client can exploit this by sending an incomplete TLS record and stopping further data transmission, causing the TLS handshake to stall indefinitely and holding connections open. By opening many such stall
No detection rules found.
No public exploits indexed.
https://github.com/traefik/traefik/releases/tag/v2.11.38https://github.com/traefik/traefik/releases/tag/v3.6.9https://github.com/traefik/traefik/security/advisories/GHSA-xw98-5q62-jx94https://access.redhat.com/errata/RHSA-2026:10175https://access.redhat.com/security/cve/CVE-2026-26999https://bugzilla.redhat.com/show_bug.cgi?id=2444874https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-26999.json
2026-03-05
Published