CVE-2025-26595: tigervnc Stack Overflow (CVSS 7.8)

Description

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.

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CVSS v3.1 Score

7.8

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Weakness Type (CWE)

CWE-121 CWE-121

CWE-787 Out-of-bounds Write

Affected Products

Vendor	Product	Versions
tigervnc	tigervnc	All
x.org	x_server	< 21.1.16
x.org	xwayland	< 24.1.6
redhat	enterprise_linux	All
redhat	enterprise_linux	All
redhat	enterprise_linux	All

References

Other References

https://access.redhat.com/errata/RHSA-2025:2500 https://access.redhat.com/errata/RHSA-2025:2502 https://access.redhat.com/errata/RHSA-2025:2861 https://access.redhat.com/errata/RHSA-2025:2862 https://access.redhat.com/errata/RHSA-2025:2865 https://access.redhat.com/errata/RHSA-2025:2866 https://access.redhat.com/errata/RHSA-2025:2873 https://access.redhat.com/errata/RHSA-2025:2874 https://access.redhat.com/errata/RHSA-2025:2875 https://access.redhat.com/errata/RHSA-2025:2879

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 7.8 (HIGH).

How severe is CVE-2025-26595? +

CVE-2025-26595 has a CVSS v3.1 score of 7.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2025-26595? +

CVE-2025-26595 affects products from redhat, tigervnc, x.org, specifically: enterprise_linux, tigervnc, x_server, xwayland. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-26595? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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