CVE-2026-50256: 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. A mismatch between the X server and the libXfont2 library's maximum font name length can cause a stack buffer overflow during font alias resolution. The server allocates a 256 byte stack buffer but libXfont2's alias target name length is 1024 bytes. A font alias name between 257 and 1023 bytes causes the X server to copy that name into the undersized stack buffer without further checks. 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 inconsistent maximum font name length handling between the X server and libXfont2. The X server allocates a 256-byte buffer for font alias names, but libXfont2 allows alias target names up to 1024 bytes. When a font alias name length exceeds 256 bytes but is less than 1024 bytes, the X server copies the name into the undersized buffer without bounds checking, causing a stack overflow. This can lead to denial of service via server crash or privilege escalation if the X server runs with root privileges. The vulnerability affects Red Hat Enterprise Linux 10 and is tracked as CVE-2026-50256 with a CVSS 3.1 score of 7.8 (high). The vendor advisory does not currently specify an available patch or remediation.
Potential Impact
The vulnerability can cause the X.Org X server or Xwayland to crash, resulting in denial of service. More critically, if the X server is running with root privileges, exploitation could lead to privilege escalation, allowing an attacker to gain elevated system access. The CVSS score of 7.8 reflects high impact on confidentiality, integrity, and availability. There are no known exploits in the wild at this time.
Mitigation Recommendations
Patch status is not yet confirmed — check the Red Hat advisory at https://access.redhat.com/security/cve/CVE-2026-50256 for current remediation guidance. Until an official fix is available, consider limiting access to the X server and running it with the least privileges possible to reduce risk. Monitor the vendor advisory for updates on patches or workarounds.
CVE-2026-50256: 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. A mismatch between the X server and the libXfont2 library's maximum font name length can cause a stack buffer overflow during font alias resolution. The server allocates a 256 byte stack buffer but libXfont2's alias target name length is 1024 bytes. A font alias name between 257 and 1023 bytes causes the X server to copy that name into the undersized stack buffer without further checks. 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 due to inconsistent maximum font name length handling between the X server and libXfont2. The X server allocates a 256-byte buffer for font alias names, but libXfont2 allows alias target names up to 1024 bytes. When a font alias name length exceeds 256 bytes but is less than 1024 bytes, the X server copies the name into the undersized buffer without bounds checking, causing a stack overflow. This can lead to denial of service via server crash or privilege escalation if the X server runs with root privileges. The vulnerability affects Red Hat Enterprise Linux 10 and is tracked as CVE-2026-50256 with a CVSS 3.1 score of 7.8 (high). The vendor advisory does not currently specify an available patch or remediation.
Potential Impact
The vulnerability can cause the X.Org X server or Xwayland to crash, resulting in denial of service. More critically, if the X server is running with root privileges, exploitation could lead to privilege escalation, allowing an attacker to gain elevated system access. The CVSS score of 7.8 reflects high impact on confidentiality, integrity, and availability. There are no known exploits in the wild at this time.
Mitigation Recommendations
Patch status is not yet confirmed — check the Red Hat advisory at https://access.redhat.com/security/cve/CVE-2026-50256 for current remediation guidance. Until an official fix is available, consider limiting access to the X server and running it with the least privileges possible to reduce risk. Monitor the vendor advisory for updates on patches or workarounds.
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-2026-50256","vendor":"Red Hat"}]
Threat ID: 6a22b798e29bf47b506379dd
Added to database: 6/5/2026, 11:48:40 AM
Last enriched: 6/5/2026, 12:04:00 PM
Last updated: 6/6/2026, 4:59:16 AM
Views: 8
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.