CVE-2026-44546: daphne WebSocket Handshake Header Smuggling Through Vulnerability

LOW
Advisory Identifier: GHSA-xh68-hfp5-5x5m
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CVSS 3.7
CWE-444
Published
Advisory Summary

CVE-2026-44546 is a LOW (CVSS 3.7) websocket handshake header smuggling through vulnerability (CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')) affecting daphne libraries in the PyPI ecosystem. The issue involves websocket handshake header smuggling through autobahn splitlines() mishandling of non-standard line separators. Remediation is available by upgrading affected packages to version 4.2.2.

CVE-2026-44546 at a Glance

CVE Identifier CVE-2026-44546
GHSA Identifier GHSA-xh68-hfp5-5x5m
Severity LOW
CVSS v3.1 Base Score 3.7
CWE Classification CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Affected Product daphne
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 3.7

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-44546

To remediate this vulnerability, upgrade all affected daphne dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

daphne fixed: 4.2.2 
pip install daphne>=4.2.2
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show daphne

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-44546, inspect your installed packages using pip:

pip show daphne

Analyze the terminal output to locate any version of daphne in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.2.2), your application is affected.

Note: The pip show daphne command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling'), where the product acts as an intermediary http agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed http requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination. In daphne, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

daphne before 4.2.2 reconstructs a raw HTTP request from Twisted's parsed headers and feeds it to autobahn for WebSocket handshake processing. Twisted does not treat \x0b, \x0c, \x1c, \x1d, \x1e, or \x85 as header line separators, but autobahn decodes header values to str and calls splitlines(). An attacker can exploit this parser differential to inject additional headers into the ASGI scope passed to the application. daphne now rejects requests with these bytes in any header value with a 400 response.

CVE-2026-44546 Affected daphne Versions

1 component(s)
Fixed Versions:
4.2.2
Product / Package Ecosystem Affected Versions Fixed Version
daphne
pypi/daphne
PyPI
< 4.2.2
4.2.2

References

NVD — CVE-2026-44546 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-44546
daphne Source Repository REPOSITORY
https://github.com/django/daphne
daphne Source Repository REPOSITORY
https://github.com/django/daphne/blob/main/CHANGELOG.txt
daphne Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/daphne/PYSEC-2026-214.yaml

Frequently Asked Questions

What is CVE-2026-44546?
CVE-2026-44546 is a security vulnerability in daphne involving WebSocket handshake header smuggling through autobahn splitlines() mishandling of non-standard line separators under CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling').
Which daphne versions are affected?
Affected versions include releases prior to 4.2.2 across affected packages: daphne.
What version fixes CVE-2026-44546?
Upgrading to 4.2.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is daphne affected?
Yes, daphne is affected in releases prior to 4.2.2. Upgrade your dependency to 4.2.2 or later.
What is the CVSS score of CVE-2026-44546?
CVE-2026-44546 has a CVSS v3.1 base score of 3.7 (LOW) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N.
What CWE is associated with CVE-2026-44546?
CVE-2026-44546 is classified under CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') (The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.).
How can I check PyPI dependencies for CVE-2026-44546?
Run the dependency tree command: 'pip show daphne'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-xh68-hfp5-5x5m",
  "modified" : "2026-07-11T22:53:35Z",
  "published" : "2026-06-03T15:30:43Z",
  "aliases" : [ "CVE-2026-44546" ],
  "summary" : "daphne: WebSocket handshake header smuggling through autobahn splitlines() mishandling of non-standard line separators",
  "details" : "daphne before 4.2.2 reconstructs a raw HTTP request from Twisted's parsed headers and feeds it to autobahn for WebSocket handshake processing. Twisted does not treat \\x0b, \\x0c, \\x1c, \\x1d, \\x1e, or \\x85 as header line separators, but autobahn decodes header values to str and calls splitlines(). An attacker can exploit this parser differential to inject additional headers into the ASGI scope passed to the application. daphne now rejects requests with these bytes in any header value with a 400 response.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "daphne"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.2.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-44546"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/django/daphne"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/django/daphne/blob/main/CHANGELOG.txt"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/daphne/PYSEC-2026-214.yaml"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-444" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-11T22:53:35Z",
    "nvd_published_at" : "2026-06-03T14:16:43Z"
  }
}