libsoup HTTP/2 UAF Auth Failure & DoS
CVE-2026-4271 Published on March 17, 2026
Libsoup: libsoup: denial of service via use-after-free in http/2 server
A flaw was found in libsoup, a library for handling HTTP requests. This vulnerability, known as a Use-After-Free, occurs in the HTTP/2 server implementation. A remote attacker can exploit this by sending specially crafted HTTP/2 requests that cause authentication failures. This can lead to the application attempting to access memory that has already been freed, potentially causing application instability or crashes, resulting in a Denial of Service (DoS).
Vulnerability Analysis
CVE-2026-4271 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. An automatable proof of concept (POC) exploit exists. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a small impact on availability.
Timeline
Reported to Red Hat.
Made public.
Weakness Type
What is a Dangling pointer Vulnerability?
Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.
CVE-2026-4271 has been classified to as a Dangling pointer vulnerability or weakness.
Products Associated with CVE-2026-4271
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Affected Versions
Red Hat Enterprise Linux 10:- Version 0:3.6.5-3.el10_1.11 and below * is unaffected.
- Version 0:3.6.5-3.el10_2.11 and below * is unaffected.
- Version 0:3.6.5-3.el10_0.15 and below * is unaffected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.