CVE-2026-93543Network attack vectorHinoki check available

Client crash via unchecked XI2 class length

Published Sep 24, 2026 · Updated Sep 24, 2026

Out-of-bounds read in X.Org libXi before 1.8.4 allows malicious X servers to crash attached X clients via crafted XI2 class data. The XI2 class parser advances through server-supplied class records without adequately validating a declared class length against the remaining reply buffer. Exploitation requires a client to connect to or otherwise use a malicious X server, and the established consequence is a client-process crash.

CVSS severity6.9
Medium
EPSS probability0.25%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
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Summary

What happened

Out-of-bounds read in X.Org libXi before 1.8.4 allows malicious X servers to crash attached X clients via crafted XI2 class data. The XI2 class parser advances through server-supplied class records without adequately validating a declared class length against the remaining reply buffer. Exploitation requires a client to connect to or otherwise use a malicious X server, and the established consequence is a client-process crash.

The record

CVE
CVE-2026-93543
Published
Sep 24, 2026
Updated
Sep 24, 2026
Vendor
The X11 Project
Product
libXi
Classifications
T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 24, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <1.8.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The X11 Project · libXiversion=0 <1.8.4

Published CVSS scores

6.9SUSECVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
6.5SUSECVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/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.

Activity data is delayed. The latest report is Sep 28, 2026.

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

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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