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 components of Red Hat Enterprise Linux 10 due to improper validation in CheckKeyTypes() of key types exceeding the maximum allowed shift levels. This allows a client to cause a stack overflow by setting key types with excessive shift levels. The issue stems from an incomplete fix of CVE-2025-26597. The vulnerability can cause denial of service by crashing the X server or potentially enable privilege escalation if the server runs as root. The CVSS 3.1 base score is 7.8 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H), indicating high impact on confidentiality, integrity, and availability.
Potential Impact
Successful exploitation can cause the X.Org X server or Xwayland to crash, resulting in denial of service. If the X server is running with root privileges, the vulnerability may also allow an attacker with local low privileges to escalate their privileges to root. The vulnerability affects confidentiality, integrity, and availability of the affected system components.
Mitigation Recommendations
Patch status is not yet confirmed — check the Red Hat advisory at https://access.redhat.com/security/cve/CVE-2026-50258 for current remediation guidance. No official fix or temporary workaround is explicitly stated in the provided vendor advisory content. Until a patch is available, restricting untrusted local user access to the X server may reduce risk.
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
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
A stack-based buffer overflow exists in the X.Org X server and Xwayland components of Red Hat Enterprise Linux 10 due to improper validation in CheckKeyTypes() of key types exceeding the maximum allowed shift levels. This allows a client to cause a stack overflow by setting key types with excessive shift levels. The issue stems from an incomplete fix of CVE-2025-26597. The vulnerability can cause denial of service by crashing the X server or potentially enable privilege escalation if the server runs as root. The CVSS 3.1 base score is 7.8 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H), indicating high impact on confidentiality, integrity, and availability.
Potential Impact
Successful exploitation can cause the X.Org X server or Xwayland to crash, resulting in denial of service. If the X server is running with root privileges, the vulnerability may also allow an attacker with local low privileges to escalate their privileges to root. The vulnerability affects confidentiality, integrity, and availability of the affected system components.
Mitigation Recommendations
Patch status is not yet confirmed — check the Red Hat advisory at https://access.redhat.com/security/cve/CVE-2026-50258 for current remediation guidance. No official fix or temporary workaround is explicitly stated in the provided vendor advisory content. Until a patch is available, restricting untrusted local user access to the X server may reduce risk.
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: 6/5/2026, 11:48:40 AM
Last enriched: 6/5/2026, 12:03:47 PM
Last updated: 6/6/2026, 4:20:38 AM
Views: 15
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