CVE-2026-4271
Libsoup: libsoup: denial of service via use-after-free in http/2 server
02 Description
Libsoup: libsoup: denial of service via use-after-free in http/2 server
03 Exploitation and scoring
- Exploitation
- Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.
- SSVC decision
- ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
- AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
- Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
- EPSS probability
- 0.86% probability of exploitation activity in the next 30 days.
- EPSS percentile
- Equal to or higher than the score of 58.1% of scored records. A rank, not a probability.
- NVD base score
- 7.5 (CVSS v3.x), scored by the NVD independently of the CNA.
- NVD CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- NVD analysis status
- Modified. NVD last modified this record on 2026-06-17.
- Red Hat severity
- Moderate. Red Hat's rating for its own products, not a CVSS rating.
Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.
04 Metadata
- Published
- 2026-03-17 11:14Z7 MO AGO
- Last updated
- 2026-05-19 21:30Z5 MO AGO
- Reserved
- 2026-03-16
- Assigning CNA
- redhat
- Record state
- PUBLISHED
- Severity
- Medium (CVSS 5.3)
- CNA CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- Weaknesses
- CWE-416Use After FreeVariant
- Data version
- 5.2
- Document digest
- 0dd9caaa1a3655b9b0f7bede748ede4bfe26add7a571c9fd37d450e035ed45fa
05 Affected products
06 References
- access.redhat.comRHSA-2026:15968https://access.redhat.com/errata/RHSA-2026:15968
- access.redhat.comRHSA-2026:17482https://access.redhat.com/errata/RHSA-2026:17482
- access.redhat.comRHSA-2026:19143https://access.redhat.com/errata/RHSA-2026:19143
- access.redhat.comhttps://access.redhat.com/security/cve/CVE-2026-4271
- bugzilla.redhat.comRHBZ#2448044https://bugzilla.redhat.com/show_bug.cgi?id=2448044
- gitlab.gnome.orghttps://gitlab.gnome.org/GNOME/libsoup/-/issues/496
07 Fixed in
AlmaLinux 10
- libsoup3 Fixed in 3.6.5-3.el10_2.11
- libsoup3-devel Fixed in 3.6.5-3.el10_2.11
- libsoup3-doc Fixed
A version is affected if any line below covers it.
- Affected before 3.6.5-3.el10_1.11
- Affected before 3.6.5-3.el10_2.11
Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.
CloudLinux 10
- libsoup3 Fixed in 3.6.5-3.el10_2.11
- libsoup3-devel Fixed in 3.6.5-3.el10_2.11
- libsoup3-doc Fixed
A version is affected if any line below covers it.
- Affected before 3.6.5-3.el10_1.11
- Affected before 3.6.5-3.el10_2.11
Derived from AlmaLinux 10. Partial coverage: only packages taken from AlmaLinux 10 are listed.
Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.
Debian 12
- libsoup2.4 No fix yet
- libsoup3 No fix yet
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 13
- libsoup2.4 No fix yet
- libsoup3 No fix yet
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 14
- libsoup3 Fixed in 3.8.0-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 24.04 LTS
- libsoup3 Fixed in 3.4.4-5ubuntu0.9
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 25.10
- libsoup3 No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 26.04 LTS
- libsoup3 Fixed in 3.6.6-1ubuntu0.1
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 26.10
- libsoup3 Fixed in 3.6.6-1ubuntu3
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.