Use After Free in Tigervnc
CVE-2025-26601
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.
Vulnerability class: Use-After-Free
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.004 (31.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 32nd percentile — 31.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- Tigervnc
- X.org X Server
- X.org Xwayland
- Red Hat Enterprise Linux 10 — versions 0:24.1.5-3.el10_0
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 6 Extended Lifecycle Support - Extension — versions 0:1.1.0-25.el6_10
- Red Hat Enterprise Linux 7 Extended Lifecycle Support — versions 0:1.8.0-36.el7_9, 0:1.20.4-30.el7_9
- Red Hat Enterprise Linux 8 — versions 0:1.13.1-15.el8_10
- Red Hat Enterprise Linux 8.2 Advanced Update Support — versions 0:1.9.0-15.el8_2.13
- Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support — versions 0:1.11.0-8.el8_4.12
Weakness classification (CWE)
Public proof-of-concept exploits
References
- access.redhat.com/errata/RHSA-2025:2500 (vendor-advisory, Third Party Advisory)
- access.redhat.com/errata/RHSA-2025:2502 (vendor-advisory, Third Party Advisory)
- access.redhat.com/errata/RHSA-2025:2861 (vendor-advisory, Third Party Advisory)
- access.redhat.com/errata/RHSA-2025:2862 (vendor-advisory, Third Party Advisory)
- access.redhat.com/errata/RHSA-2025:2865 (vendor-advisory, Third Party Advisory)
- access.redhat.com/errata/RHSA-2025:2866 (vendor-advisory, Third Party Advisory)
- access.redhat.com/errata/RHSA-2025:2873 (vendor-advisory, Third Party Advisory)
- access.redhat.com/errata/RHSA-2025:2874 (vendor-advisory, Third Party Advisory)
- access.redhat.com/errata/RHSA-2025:2875 (vendor-advisory, Third Party Advisory)
- access.redhat.com/errata/RHSA-2025:2879 (vendor-advisory, Third Party Advisory)
Frequently asked questions
- What is CVE-2025-26601?
- CVE-2025-26601 is a high-severity vulnerability in Tigervnc, classified under Use After Free. CVSS score: 7.8/10. Published 2025-02-25.
- How severe is CVE-2025-26601?
- High severity. CVSS v3 base score is 7.8 out of 10.
- Is CVE-2025-26601 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.