CVE-2026-50256Hinoki check available

Root escalation via unchecked font alias copy

Published Jun 5, 2026 · Updated Jun 5, 2026

Stack-based buffer overflow in X.Org X server components on RHEL 7 through 10 allows local users to crash the server or gain root privileges. Font alias resolution copies a libXfont2 alias target of up to 1,024 bytes into a 256-byte stack buffer without a matching length check. Exploitation requires local low-privileged access; privilege escalation applies when the affected X server runs as root, while other cases can terminate the display server.

CVSS severity7.8
High
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
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Summary

What happened

Stack-based buffer overflow in X.Org X server components on RHEL 7 through 10 allows local users to crash the server or gain root privileges. Font alias resolution copies a libXfont2 alias target of up to 1,024 bytes into a 256-byte stack buffer without a matching length check. Exploitation requires local low-privileged access; privilege escalation applies when the affected X server runs as root, while other cases can terminate the display server.

The record

CVE
CVE-2026-50256
Published
Jun 5, 2026
Updated
Jun 5, 2026
Vendor
389 Directory Server
Product
Red Hat Enterprise Linux 10
Classifications
CWE-121, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 5, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

389 Directory Server · Red Hat Enterprise Linux 10Affected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 7Affected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 9Affected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8Affected versions are unavailable in this record.

Published CVSS scores

7.8Red HatCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-121Stack-based Buffer Overflow
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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