CVE-2025-57804
Description
A vulnerability was found in python-hyper/h2 that contains an input validation flaw that allows carriage return and line feed (CRLF) characters to be injected into HTTP/2 header fields. When requests are downgraded from HTTP/2 to HTTP/1.1, the library fails to enforce proper header validation, which may lead to incorrect parsing of request boundaries by downstream components.
Statement
This issue is classified as Moderate rather than Important because its impact is constrained to integrity violations through request injection, without directly compromising confidentiality or availability. The flaw arises only in environments where HTTP/2 traffic is downgraded to HTTP/1.1 by intermediaries, which is not the default behavior in many deployments. Successful exploitation requires specific backend or proxy configurations that fail to sanitize CRLF sequences properly. As a result, the vulnerability does not universally expose systems to privilege escalation or data leakage but instead enables request manipulation under certain conditions.
Mitigation
Mitigation is either unavailable or does not meet Red Hat Product Security standards for usability, deployment, applicability, or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.3 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | None | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | Low | N/A | N/A |
| Availability Impact | None | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Application Data
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