CVE-2025-26596

Local code execution via XKB length miscalculation

Published Feb 25, 2025 · Updated Jun 29, 2026

Heap overflow in X.Org X Server and Xwayland before 21.1.16 and 24.1.6 allows local users to execute code via crafted XKB data. XkbSizeKeySyms calculates less reply storage than XkbWriteKeySyms can serialize when per-key symbol counts exceed the width encoded in the key map. A low-privileged local X client can corrupt the server heap; on RHEL 8 and 9, the X server does not run as root.

CVSS severity7.8
High
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap overflow in X.Org X Server and Xwayland before 21.1.16 and 24.1.6 allows local users to execute code via crafted XKB data. XkbSizeKeySyms calculates less reply storage than XkbWriteKeySyms can serialize when per-key symbol counts exceed the width encoded in the key map. A low-privileged local X client can corrupt the server heap; on RHEL 8 and 9, the X server does not run as root.

The record

CVE
CVE-2025-26596
Published
Feb 25, 2025
Updated
Jun 29, 2026
Vendor
389 Directory Server
Product
Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions
Classifications
CWE-122
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 25, 2025CVE publishedPublication date reported by the CVE source.
  2. Jun 29, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

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 8.6 Update Services for SAP SolutionsAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 9.2 Extended Update SupportAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8.6 Telecommunications Update ServiceAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 10Affected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 6 Extended Lifecycle Support - ExtensionAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8.8 Extended Update SupportAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 9.4 Extended Update SupportAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8.4 Update Services for SAP SolutionsAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8.4 Telecommunications Update ServiceAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update SupportAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8.2 Advanced Update SupportAffected 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 9.0 Update Services for SAP SolutionsAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 7 Extended Lifecycle SupportAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update SupportAffected 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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-122Heap-based Buffer Overflow

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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