CVE-2026-50258: Stack-based Buffer Overflow in Red Hat Red Hat Enterprise Linux 10
A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. The X server has multiple stack buffers sized XkbMaxShiftLevel * XkbNumKbdGroups but CheckKeyTypes() does not verify or clamp non-canonical key types to XkbMaxShiftLevel. A client can change key types to excessive shift levels and trigger stack overflows. This is caused by an incomplete fix of CVE-2025-26597. This may be used to crash the server, or for privilege escalation if the X server runs as root.
AI Analysis
Technical Summary
A stack-based buffer overflow exists in the X.Org X server and Xwayland due to improper validation in CheckKeyTypes() of key types exceeding the maximum allowed shift levels (XkbMaxShiftLevel). This allows a client to cause stack overflows by changing key types to excessive shift levels. The issue is linked to an incomplete fix of CVE-2025-26597. Red Hat Enterprise Linux 10 versions prior to 10.2.2 are affected. Red Hat has released patches in xorg-x11-server and xorg-x11-server-Xwayland packages to fix this vulnerability as part of a broader security update addressing multiple related issues.
Potential Impact
Successful exploitation can cause a stack-based buffer overflow leading to denial of service (server crash) or privilege escalation if the X server is running as root. The vulnerability affects the confidentiality, integrity, and availability of the system, as indicated by the CVSS vector (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).
Mitigation Recommendations
Red Hat has released official patches fixing this vulnerability in xorg-x11-server and xorg-x11-server-Xwayland packages for Red Hat Enterprise Linux 10. Users should apply the updates provided in Red Hat Security Advisories RHSA-2026:26566 and RHSA-2026:26562 or later to remediate this issue. For detailed update instructions, refer to https://access.redhat.com/articles/11258. No additional mitigation steps are required beyond applying the official fixes.
CVE-2026-50258: Stack-based Buffer Overflow in Red Hat Red Hat Enterprise Linux 10
Description
A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. The X server has multiple stack buffers sized XkbMaxShiftLevel * XkbNumKbdGroups but CheckKeyTypes() does not verify or clamp non-canonical key types to XkbMaxShiftLevel. A client can change key types to excessive shift levels and trigger stack overflows. This is caused by an incomplete fix of CVE-2025-26597. This may be used to crash the server, or for privilege escalation if the X server runs as root.
CVSS v3.1
Score 7.8high
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
A stack-based buffer overflow exists in the X.Org X server and Xwayland due to improper validation in CheckKeyTypes() of key types exceeding the maximum allowed shift levels (XkbMaxShiftLevel). This allows a client to cause stack overflows by changing key types to excessive shift levels. The issue is linked to an incomplete fix of CVE-2025-26597. Red Hat Enterprise Linux 10 versions prior to 10.2.2 are affected. Red Hat has released patches in xorg-x11-server and xorg-x11-server-Xwayland packages to fix this vulnerability as part of a broader security update addressing multiple related issues.
Potential Impact
Successful exploitation can cause a stack-based buffer overflow leading to denial of service (server crash) or privilege escalation if the X server is running as root. The vulnerability affects the confidentiality, integrity, and availability of the system, as indicated by the CVSS vector (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).
Mitigation Recommendations
Red Hat has released official patches fixing this vulnerability in xorg-x11-server and xorg-x11-server-Xwayland packages for Red Hat Enterprise Linux 10. Users should apply the updates provided in Red Hat Security Advisories RHSA-2026:26566 and RHSA-2026:26562 or later to remediate this issue. For detailed update instructions, refer to https://access.redhat.com/articles/11258. No additional mitigation steps are required beyond applying the official fixes.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- redhat
- Date Reserved
- 2026-06-04T14:55:24.011Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
- Vendor Advisory Urls
- [{"url":"https://access.redhat.com/security/cve/CVE-2026-50258","vendor":"Red Hat"}]
Threat ID: 6a22b798e29bf47b506379eb
Added to database: 06/05/2026, 11:48:40 UTC
Last enriched: 07/30/2026, 01:42:10 UTC
Last updated: 07/31/2026, 19:30:23 UTC
Views: 106
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