CVE-2026-19773
Description
A flaw was found in libwebsockets. This vulnerability allows an unauthenticated remote attacker to achieve arbitrary code execution by sending specially crafted HTTP/2 network traffic. The issue occurs due to improper input validation during the parsing of path headers compressed with HPACK (a header compression format used in HTTP/2), which causes an out-of-bounds write beyond an allocated memory buffer. As a result, an attacker can execute arbitrary commands or cause a denial of service within the context of the affected process.
Statement
This flaw is rated as Critical severity for Red Hat products because an unauthenticated remote attacker can achieve code execution over the network with no user interaction. Within Red Hat enterprise environments, libwebsockets functions as an underlying shared library supporting network services, making any listening service that negotiates HTTP/2 directly vulnerable to memory corruption. Exploitation requires the target daemon to process untrusted HTTP/2 traffic; deployments that exclusively serve HTTP/1.1 or do not expose network endpoints to untrusted clients face reduced practical risk.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, 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 | 9.8 | N/A | 9.8 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
Write operations could cause memory corruption. In some cases, an adversary can modify control data such as return addresses in order to execute unexpected code.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
Attempting to access out-of-range, invalid, or unauthorized memory could cause the product to crash.
Other
Technical Impact: Unexpected State
Subsequent write operations can produce undefined or unexpected results.
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