CVE-2026-34002 | Xorg: xwayland: x.org x server: information disclosure or denial of service via out-of-bounds read in xkb modifier map handling

A flaw was found in the X.Org X server. This vulnerability, an out-of-bounds read, affects the XKB (X Keyboard Extension) modifier map handling. An attacker with access to the X11 server can exploit this by sending a malformed request, which causes the server to read beyond its intended memory boundaries. This can lead to the exposure of sensitive information or cause the server to crash, resulting in a denial of service.

Published: 2026-05-05 Last update: 2026-06-04 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2026-34002 is rated Low Risk (25/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.01%). Mandatory action: Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-34002

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-06 0.01%

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-34002

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.1 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:L Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
1.8 4.2 [email protected]
9.1 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
3.9 5.2 [email protected]

Weakness enumeration for CVE-2026-34002

GitHub Security Advisory for CVE-2026-34002

GHSA-2q6x-pg74-2276 · Severity: medium — A flaw was found in the X.Org X server. This vulnerability, an out-of-bounds read, affects the...

OS Trackers for CVE-2026-34002

vendor priority summary link
debian not yet assigned CVE-2026-34002 not yet assigned priority: Debian including 2 source packages (xorg-server, xwayland), 9 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 6, open 3. https://security-tracker.debian.org/tracker/CVE-2026-34002
redhat medium https://access.redhat.com/security/cve/CVE-2026-34002
suse medium https://www.suse.com/security/cve/CVE-2026-34002/
ubuntu medium CVE-2026-34002 medium priority: Ubuntu including 7 source packages (xorg, xorg-hwe-16.04, …), 46 status rows across 9 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream, xenial): DNE 16, needs-triage 16, not-affected 12, released 2. https://ubuntu.com/security/CVE-2026-34002

Affected software / configurations for CVE-2026-34002

Vendor Product Version Raw CPE
x.org x_server cpe:2.3:a:x.org:x_server:-:*:*:*:*:*:*:*
redhat enterprise_linux 6.0 cpe:2.3:o:redhat:enterprise_linux:6.0:*:*:*:*:*:*:*
redhat enterprise_linux 7.0 cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
redhat enterprise_linux 8.0 cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
redhat enterprise_linux 9.0 cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*
redhat enterprise_linux 10.0 cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:*

References for CVE-2026-34002

URL Tags
https://access.redhat.com/errata/RHSA-2026:20547
https://access.redhat.com/errata/RHSA-2026:20555
https://access.redhat.com/errata/RHSA-2026:20557
https://access.redhat.com/errata/RHSA-2026:20558
https://access.redhat.com/errata/RHSA-2026:20560
https://access.redhat.com/errata/RHSA-2026:20561
https://access.redhat.com/errata/RHSA-2026:20562
https://access.redhat.com/errata/RHSA-2026:20563
https://access.redhat.com/errata/RHSA-2026:20575
https://access.redhat.com/errata/RHSA-2026:20576
https://access.redhat.com/errata/RHSA-2026:20590
https://access.redhat.com/errata/RHSA-2026:21699
https://access.redhat.com/errata/RHSA-2026:21712
https://access.redhat.com/errata/RHSA-2026:21715
https://access.redhat.com/errata/RHSA-2026:21716
https://access.redhat.com/errata/RHSA-2026:21718
https://access.redhat.com/errata/RHSA-2026:21741
https://access.redhat.com/errata/RHSA-2026:21742
https://access.redhat.com/errata/RHSA-2026:22424
https://access.redhat.com/errata/RHSA-2026:22456
https://access.redhat.com/errata/RHSA-2026:23254
https://access.redhat.com/errata/RHSA-2026:23255
https://access.redhat.com/security/cve/CVE-2026-34002 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2451112 Issue Tracking Third Party Advisory
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