CVE-2026-73051Network attack vectorHinoki check available

Request smuggling via conflicting HTTP framing headers

Published Aug 14, 2026 · Updated Aug 14, 2026

HTTP request smuggling in Actix Web allows remote attackers to inject backend requests via conflicting HTTP/1.1 framing headers. The actix-http parser accepts both Content-Length and Transfer-Encoding: chunked, then chooses chunked decoding rather than rejecting the ambiguous request. Exploitation requires a front-end intermediary that honors Content-Length while reusing an HTTP/1.1 connection to the Actix backend; no credentials or user interaction are required.

CVSS severity6.3
Medium
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

HTTP request smuggling in Actix Web allows remote attackers to inject backend requests via conflicting HTTP/1.1 framing headers. The actix-http parser accepts both Content-Length and Transfer-Encoding: chunked, then chooses chunked decoding rather than rejecting the ambiguous request. Exploitation requires a front-end intermediary that honors Content-Length while reusing an HTTP/1.1 connection to the Actix backend; no credentials or user interaction are required.

The record

CVE
CVE-2026-73051
Published
Aug 14, 2026
Updated
Aug 14, 2026
Vendor
Actix
Product
Actix Web
Classifications
CWE-444, CAPEC-33, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=0 <3.12.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Actix · Actix Webversion=0 <3.12.0

Published CVSS scores

6.3VulnCheckCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
6.3GitHub Advisory DatabaseCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
CAPEC-33HTTP Request Smuggling
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo