CVE-2026-4271 Libsoup: libsoup: denial of service via use-after-free in http/2 server
Remote attackers can cause denial of service in applications using libsoup's HTTP/2 server by triggering a use-after-free via crafted requests.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-4271?
CVE-2026-4271 is a medium-severity use after free vulnerability in Redhat Enterprise Linux, published on 17 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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).
Weakness: CWE-416
Which versions are affected by CVE-2026-4271?
It affects 2 products.
Linux distribution packages (3)
libsoup SUSE:Linux Enterprise Server 16.0 | All versions | 3.6.6-160000.2.1 |
libsoup SUSE:Linux Enterprise Server for SAP applications 16.0 | All versions | 3.6.6-160000.2.1 |
libsoup openSUSE:Tumbleweed | All versions | 3.6.6-5.1 |
Products include Gnome Libsoup, Redhat Enterprise Linux.
How do I fix CVE-2026-4271?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-4271 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-4271 exists.
Other vulnerabilities in Redhat Enterprise Linux
- CVE-2026-102556 Libsoup: libsoup: heap buffer overflow from websocket pong signal type confusion
- CVE-2026-102557 Libsoup: libsoup: heap buffer overflow during websocket message reassembly
- CVE-2026-102558 Libsoup: libsoup: heap buffer overflow during websocket receive-buffer growth
- CVE-2026-102559 Libsoup: libsoup: heap buffer overflow during websocket client-frame masking
- CVE-2026-102560 Libsoup: libsoup: heap buffer overflow during outgoing permessage-deflate buffer growth
Sources
Also known as DEBIAN-CVE-2026-4271, ECHO-8792-9c43-a7ba, GHSA-xxmc-fm3p-q3x8, ROOT-OS-DEBIAN-13-CVE-2026-4271, SUSE-SU-2026:21879-1, SUSE-SU-2026:21946-1 and 5 more.