CVE-2025-26601 | Xorg: xwayland: use-after-free in syncinittrigger()

A use-after-free flaw was found in X.Org and Xwayland. When changing an alarm, the values of the change mask are evaluated one after the other, changing the trigger values as requested, and eventually, SyncInitTrigger() is called. If one of the changes triggers an error, the function will return early, not adding the new sync object, possibly causing a use-after-free when the alarm eventually triggers.

Published: 2025-02-25 Last update: 2026-04-06 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-26601 is rated Moderate Risk (40.9/100): CVSS High severity, with low exploitation likelihood (EPSS 0.35%). 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-2025-26601

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 0.02% 0.35% +0.33%
2 2026-04-05 0.05% 0.02% -0.03%
3 2025-12-22 — 0.05% —

Full EPSS history (6 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-26601

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.8 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
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:L)
A normal user session is enough; they don’t have to be admin.
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:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 5.9 [email protected]
7.8 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
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:L)
A normal user session is enough; they don’t have to be admin.
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:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 5.9 [email protected]

Weakness enumeration for CVE-2025-26601

OS Trackers for CVE-2025-26601

vendor priority summary link
alpine — CVE-2025-26601: 2 source package rows (xorg-server, xwayland); 6 state rows across 3 repos (3.21-community, 3.22-community, edge-community); fixed 6, open 0. https://security.alpinelinux.org/vuln/CVE-2025-26601
debian not yet assigned CVE-2025-26601 not yet assigned priority: Debian including 2 source packages (xorg-server, xwayland), 9 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 8, open 1. https://security-tracker.debian.org/tracker/CVE-2025-26601
gentoo high CVE-2025-26601: 1 GLSA(s) (202506-04), 2 atom(s) (x11-base/xorg-server, x11-base/xwayland); latest impact high. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2025-26601
redhat high — https://access.redhat.com/security/cve/CVE-2025-26601
suse high CVE-2025-26601 severity important: SUSE including 310 source package names (21:xorg-x11-server-21.1.11-150600.5.6.1, 21:xorg-x11-server-Xvfb-21.1.11-150600.5.6.1, …), 394 product×package rows across 58 product lines (Container suse/kiosk/xorg, Image SLES15-SP3-SAPCAL-Azure, … (58 product lines)): Known Affected 231, Fixed 162, Known Not Affected 1. https://www.suse.com/security/cve/CVE-2025-26601/
ubuntu medium CVE-2025-26601 medium priority: Ubuntu including 7 source packages (xorg, xorg-hwe-16.04, …), 58 status rows across 10 suites (bionic, focal, jammy, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 25, released 17, not-affected 13, needs-triage 3. https://ubuntu.com/security/CVE-2025-26601

Affected software / configurations for CVE-2025-26601

Vendor Product Version Raw CPE
tigervnc tigervnc — cpe:2.3:a:tigervnc:tigervnc:-:*:*:*:*:*:*:*
x.org x_server < 21.1.16 cpe:2.3:a:x.org:x_server:*:*:*:*:*:*:*:*
x.org xwayland < 24.1.6 cpe:2.3:a:x.org:xwayland:*:*:*:*:*:*:*:*
redhat enterprise_linux 7.0 cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
redhat enterprise_linux 8.0 cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
redhat enterprise_linux 9.0 cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*

References for CVE-2025-26601

URL Tags
https://access.redhat.com/errata/RHSA-2025:2500 Third Party Advisory
https://access.redhat.com/errata/RHSA-2025:2502 Third Party Advisory
https://access.redhat.com/errata/RHSA-2025:2861 Third Party Advisory
https://access.redhat.com/errata/RHSA-2025:2862 Third Party Advisory
https://access.redhat.com/errata/RHSA-2025:2865 Third Party Advisory
https://access.redhat.com/errata/RHSA-2025:2866 Third Party Advisory
https://access.redhat.com/errata/RHSA-2025:2873 Third Party Advisory
https://access.redhat.com/errata/RHSA-2025:2874 Third Party Advisory
https://access.redhat.com/errata/RHSA-2025:2875 Third Party Advisory
https://access.redhat.com/errata/RHSA-2025:2879 Third Party Advisory
https://access.redhat.com/errata/RHSA-2025:2880 Third Party Advisory
https://access.redhat.com/errata/RHSA-2025:3976
https://access.redhat.com/errata/RHSA-2025:7163
https://access.redhat.com/errata/RHSA-2025:7165
https://access.redhat.com/errata/RHSA-2025:7458
https://access.redhat.com/security/cve/CVE-2025-26601 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2345251 Issue Tracking
https://lists.debian.org/debian-lts-announce/2025/02/msg00036.html
https://security.netapp.com/advisory/ntap-20250516-0004/
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