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GHSA-847f-9342-265h | Mondoo Vulnerability Intelligence

Vulnerability IntelligenceGHSA-847f-9342-265h

GHSA-847f-9342-265h

MEDIUM6.9

h2 allows HTTP Request Smuggling due to illegal characters in headers

Published Aug 25, 2025

Modified 11 months ago

Fix available

Details

Summary

HTTP/2 request splitting vulnerability allows attackers to perform request smuggling attacks by injecting CRLF characters into headers. This occurs when servers downgrade HTTP/2 requests to HTTP/1.1 without properly validating header names/values, enabling attackers to manipulate request boundaries and bypass security controls.

Affected Packages

h2

PyPI

Fixed in:

4.3.0

References

https://github.com/advisories/GHSA-847f-9342-265h

https://github.com/python-hyper/h2

https://github.com/python-hyper/h2/commit/035e9899f95e3709af098f578bfc3cd302298e3a

https://github.com/python-hyper/h2/security/advisories/GHSA-847f-9342-265h

https://lists.debian.org/debian-lts-announce/2025/09/msg00004.html

https://nvd.nist.gov/vuln/detail/CVE-2025-57804

Aliases

CVSS Analysis

CVSS v4.0

6.9

Exploitability

Attack Vector

NetworkAV:N

Attack Complexity

LowAC:L

Attack Requirements

NoneAT:N

Privileges Required

NonePR:N

User Interaction

NoneUI:N

Vulnerable System

Vuln. Confidentiality

NoneVC:N

Vuln. Integrity

NoneVI:N

Vuln. Availability

NoneVA:N

Subsequent System

Subseq. Confidentiality

NoneSC:N

Subseq. Integrity

LowSI:L

Subseq. Availability

NoneSA:N

6.9/CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N

Related

Ecosystems

Timeline

PublishedAug 25, 2025

ModifiedNov 3, 2025