CVE-2026-71324Public exploitNetwork attack vector

Cross-user response poisoning via unframed CONNECT bodies

Published Aug 6, 2026 · Updated Aug 6, 2026

Response smuggling in Traefik Proxy before 2.11.53, 3.0.0 through 3.6.23, or 3.7.0 through 3.7.8 lets remote attackers poison cross-user responses. The default httputil reverse proxy writes an HTTP/2 or HTTP/3 CONNECT body unframed to an HTTP/1.1 upstream, then returns the desynchronized socket to its shared idle pool after a keep-alive non-2xx response. Exploitation requires an upstream that leaves the CONNECT body undrained; another client can receive attacker-chosen, authenticated, or private content.

CVSS severity7.0
High
EPSS probability0.55%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Response smuggling in Traefik Proxy before 2.11.53, 3.0.0 through 3.6.23, or 3.7.0 through 3.7.8 lets remote attackers poison cross-user responses. The default httputil reverse proxy writes an HTTP/2 or HTTP/3 CONNECT body unframed to an HTTP/1.1 upstream, then returns the desynchronized socket to its shared idle pool after a keep-alive non-2xx response. Exploitation requires an upstream that leaves the CONNECT body undrained; another client can receive attacker-chosen, authenticated, or private content.

The record

CVE
CVE-2026-71324
Published
Aug 6, 2026
Updated
Aug 6, 2026
Vendor
Traefik Labs
Product
Traefik Proxy
Classifications
CWE-444, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 6, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 6, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.11.53
  2. Affected versionversion=>= 3.0.0, < 3.6.24
  3. Affected versionversion=>= 3.7.0, < 3.7.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Traefik Labs · Traefik Proxyversion=< 2.11.53; version=>= 3.0.0, < 3.6.24; version=>= 3.7.0, < 3.7.9

Published CVSS scores

7.0GitHubCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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