CVE-2026-4271: Libsoup: libsoup: denial of service via use-after-free in http/2 server

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.9% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-03-17 · updated 2026-06-17
Weakness: CWE-416

Description

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).

Affected products

GNOME libsoup: all versions
Red Hat Enterprise Linux: 6.0, 7.0, 8.0, 9.0, 10.0

References

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