Red Hat Enterprise Linux 10.0 Extended Update…: Out-of-bounds Read
CVE-2026-34000 is a critical-severity out-of-bounds read vulnerability in Red Hat Enterprise Linux 10.0 Extended Update Support from Red Hat, with a CVSS 3.1 base score of 9.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. There is no confirmed exploitation so far. EPSS estimates a 0.49% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of Red Hat Enterprise Linux 10.0 Extended Update Support you run against the affected versions below, and install the vendor's latest release.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 6.1 | Medium | CNA (redhat.com) |
| CVSS 3.1 | 9.1 | Critical | NVD |
Official description
A flaw was found in the X.Org X server. This out-of-bounds read vulnerability in the XKB geometry processing, specifically within the `CheckSetGeom()` and `XkbAddGeomKeyAlias` functions, allows an attacker to read uninitialized or out-of-bounds memory. An attacker with a connection to the X11 server, either locally or remotely, can exploit this without user interaction. This could lead to the disclosure of memory contents or cause a denial of service by crashing the server.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Read
The product reads data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that provides appropriate memory abstractions.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- access.redhat.com/security/cve/CVE-2026-34000Third Party Advisory
- bugzilla.redhat.com/show_bug.cgi?id=2451107Issue Tracking, Third Party Advisory
Other references
- access.redhat.com/errata/RHSA-2026:19342
- access.redhat.com/errata/RHSA-2026:20547
- access.redhat.com/errata/RHSA-2026:20555
- access.redhat.com/errata/RHSA-2026:20557
- access.redhat.com/errata/RHSA-2026:20558
- access.redhat.com/errata/RHSA-2026:20560
- access.redhat.com/errata/RHSA-2026:20561
- access.redhat.com/errata/RHSA-2026:20562
- access.redhat.com/errata/RHSA-2026:20563
- access.redhat.com/errata/RHSA-2026:20575
- access.redhat.com/errata/RHSA-2026:20576
- access.redhat.com/errata/RHSA-2026:20590
- access.redhat.com/errata/RHSA-2026:21699
- access.redhat.com/errata/RHSA-2026:21712
- access.redhat.com/errata/RHSA-2026:21715
Other vulnerabilities in Red Hat Enterprise Linux 10.0 Extended Update Support
- 9.8 Critical severity
- 8.6 High severity
- 8.6 High severity
- 8.2 High severity
- 8.6 High severity
- 8.6 High severity
Recent Out-of-bounds Read vulnerabilities
- 7.5 High severity
- 9.1 Critical severity
- 7.8 High severity
- 7.5 High severity
- 9.1 Critical severity
- 8.1 High severity
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