---
id: CVE-2021-45960
title: >-
  In Expat (aka libexpat) before 2.4.3, a left shift by 29 (or more) places in
  the storeAtts function in xmlparse.c can lead to realloc misbehavior (e.g.,
  allocating too few bytes, or only freeing memory).
summary: >-
  In Expat (aka libexpat) before 2.4.3, a left shift by 29 (or more) places in
  the storeAtts function in xmlparse.c can lead to realloc misbehavior (e.g.,
  allocating too few bytes, or only freeing memory).
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-682
  - CWE-682
vendor: libexpat_project
product: libexpat
affected:
  - libexpat < 2.4.3
  - nessus < 8.15.3
  - 'nessus >= 10.0.0, < 10.1.1'
  - debian_linux = 10.0
  - debian_linux = 11.0
  - sinema_remote_connect_server < 3.1
  - active_iq_unified_manager
  - hci_baseboard_management_controller = h610c
  - hci_baseboard_management_controller = h610s
  - hci_baseboard_management_controller = h615c
  - oncommand_workflow_automation
  - solidfire_&_hci_management_node
patched:
  - libexpat 2.4.3
  - nessus 10.1.1
  - sinema_remote_connect_server 3.1
published: '2022-01-01'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T13:17:10.723'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-45960'
references:
  - url: 'http://www.openwall.com/lists/oss-security/2022/01/17/3'
    label: cve@mitre.org
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=1217609'
    label: cve@mitre.org
  - url: 'https://cert-portal.siemens.com/productcert/pdf/ssa-484086.pdf'
    label: cve@mitre.org
  - url: 'https://github.com/libexpat/libexpat/issues/531'
    label: cve@mitre.org
  - url: 'https://github.com/libexpat/libexpat/pull/534'
    label: cve@mitre.org
  - url: 'https://security.gentoo.org/glsa/202209-24'
    label: cve@mitre.org
  - url: 'https://security.netapp.com/advisory/ntap-20220121-0004/'
    label: cve@mitre.org
  - url: 'https://www.debian.org/security/2022/dsa-5073'
    label: cve@mitre.org
  - url: 'https://www.tenable.com/security/tns-2022-05'
    label: cve@mitre.org
  - url: 'http://www.openwall.com/lists/oss-security/2022/01/17/3'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=1217609'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/pdf/ssa-484086.pdf'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://github.com/libexpat/libexpat/issues/531'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://github.com/libexpat/libexpat/pull/534'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.gentoo.org/glsa/202209-24'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.netapp.com/advisory/ntap-20220121-0004/'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.debian.org/security/2022/dsa-5073'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.tenable.com/security/tns-2022-05'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-398330.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-484086.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - exploit-available
epss: 0.04234
epssPercentile: 0.90811
exploits:
  github: 2
  githubRepos:
    - 'https://github.com/nanopathi/external_expat_AOSP10_r33_CVE-2021-45960'
    - >-
      https://github.com/Trinadh465/external_lib_AOSP10_r33_CVE-2021-45960_CVE-2021-46143-
  checkedAt: '2026-10-14T13:31:34.728Z'
exploitAvailable: true
ingestedAt: '2026-10-14T13:30:58.407Z'
---

## Overview

In Expat (aka libexpat) before 2.4.3, a left shift by 29 (or more) places in the storeAtts function in xmlparse.c can lead to realloc misbehavior (e.g., allocating too few bytes, or only freeing memory).

## Affected

- `libexpat < 2.4.3`
- `nessus < 8.15.3`
- `nessus >= 10.0.0, < 10.1.1`
- `debian_linux = 10.0`
- `debian_linux = 11.0`
- `sinema_remote_connect_server < 3.1`
- `active_iq_unified_manager`
- `hci_baseboard_management_controller = h610c`
- `hci_baseboard_management_controller = h610s`
- `hci_baseboard_management_controller = h615c`
- `oncommand_workflow_automation`
- `solidfire_&_hci_management_node`

## Remediation

Upgrade past the affected range:

- `libexpat 2.4.3`
- `nessus 10.1.1`
- `sinema_remote_connect_server 3.1`