Buffer overflow in Tigervnc
CVE-2025-26595
A buffer overflow flaw was found in X.Org and Xwayland. The code in XkbVModMaskText() allocates a fixed-sized buffer on the stack and copies the names of the virtual modifiers to that buffer. The code fails to check the bounds of the buffer and would copy the data regardless of the size.
Vulnerability class: Buffer Overflow
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 (36.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 37th percentile — 36.7% 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-2025-26595?
- CVE-2025-26595 is a high-severity vulnerability in Tigervnc, classified under Stack-based Buffer Overflow. CVSS score: 7.8/10. Published 2025-02-25.
- How severe is CVE-2025-26595?
- High severity. CVSS v3 base score is 7.8 out of 10.
- Is CVE-2025-26595 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.