What’s Vulnerable › Vulnerabilities

CVE-2025-26596: Xorg: xwayland: heap overflow in xkbwritekeysyms()

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-02-25 · updated 2026-06-29
• Weakness: CWE-787

Description

A heap overflow flaw was found in X.Org and Xwayland. The computation of the length in XkbSizeKeySyms() differs from what is written in XkbWriteKeySyms(), which may lead to a heap-based buffer overflow.

Affected products

• Red Hat Enterprise Linux: 7.0, 8.0, 9.0
• Kaspersky TigerVNC: all versions
• xorg-x11-server: before 21.1.16 — fixed in 21.1.16
• X.Org xwayland: before 24.1.6 — fixed in 24.1.6

How to fix

Upgrade to a fixed version: xorg-x11-server 21.1.16; X.Org xwayland 24.1.6. Check the vendor advisory for mitigations.

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
• https://access.redhat.com/errata/RHSA-2025:2880
• https://access.redhat.com/errata/RHSA-2025:3976

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