CVE-2025-11021 | Libsoup: out-of-bounds read in cookie date handling of libsoup http library

A flaw was found in the cookie date handling logic of the libsoup HTTP library, widely used by GNOME and other applications for web communication. When processing cookies with specially crafted expiration dates, the library may perform an out-of-bounds memory read. This flaw could result in unintended disclosure of memory contents, potentially exposing sensitive information from the process using libsoup.

Published: 2025-09-26 Last update: 2026-04-15 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2025-11021 is rated Moderate Risk (43.3/100): CVSS High severity, with low exploitation likelihood (EPSS 0.47%). Mandatory action: Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-11021

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.07% 0.47% +0.40%
2 2026-03-06 0.05% 0.07% +0.02%
3 2026-02-22 0.05%

Full EPSS history (5 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-11021

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
3.9 3.6 [email protected]

Weakness enumeration for CVE-2025-11021

OS Trackers for CVE-2025-11021

vendor priority summary link
debian not yet assigned CVE-2025-11021 not yet assigned priority: Debian including 1 source packages (libsoup3), 4 status rows across 4 suites (bookworm, forky, sid, trixie): open 2, resolved 2. https://security-tracker.debian.org/tracker/CVE-2025-11021
redhat high https://access.redhat.com/security/cve/CVE-2025-11021
suse high CVE-2025-11021 severity important: SUSE including 36 source package names (13.2-9.1:libsqlite3-0-3.49.1-1.1, 13.2-9.1:strace-6.7-2.1, …), 111 product×package rows across 42 product lines (Container suse/sl-micro/6.0/baremetal-os-container, Container suse/sl-micro/6.0/base-os-container, … (42 product lines)): Fixed 107, First Fixed 4. https://www.suse.com/security/cve/CVE-2025-11021/
ubuntu medium CVE-2025-11021 medium priority: Ubuntu including 2 source packages (libsoup2.4, libsoup3), 13 status rows across 8 suites (bionic, focal, jammy, noble, plucky, questing, upstream, xenial): released 11, needs-triage 2. https://ubuntu.com/security/CVE-2025-11021

Affected software / configurations for CVE-2025-11021

Vendor Product Version Raw CPE
No affected products in dataset.

References for CVE-2025-11021

URL Tags
https://access.redhat.com/errata/RHSA-2025:18183
https://access.redhat.com/errata/RHSA-2025:19713
https://access.redhat.com/errata/RHSA-2025:19714
https://access.redhat.com/errata/RHSA-2025:20959
https://access.redhat.com/errata/RHSA-2025:21032
https://access.redhat.com/errata/RHSA-2025:21655
https://access.redhat.com/errata/RHSA-2025:21656
https://access.redhat.com/errata/RHSA-2025:21657
https://access.redhat.com/errata/RHSA-2025:21664
https://access.redhat.com/errata/RHSA-2025:21665
https://access.redhat.com/errata/RHSA-2025:21666
https://access.redhat.com/errata/RHSA-2025:21772
https://access.redhat.com/errata/RHSA-2025:22013
https://access.redhat.com/security/cve/CVE-2025-11021
https://bugzilla.redhat.com/show_bug.cgi?id=2399627
https://gitlab.gnome.org/GNOME/libsoup/-/issues/459
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