# CVE-2025-8040: Memory safety bugs fixed in Firefox ESR 140.1, Thunderbird ESR 140.1, Firefox 141 and Thunderbird 141

> Memory safety bugs in Firefox and Thunderbird allow arbitrary code execution, requiring users to upgrade to the latest versions.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 22 Jul 2025
- **Updated:** 13 Apr 2026
- **Also known as:** GHSA-7jcf-w576-jvj3, UBUNTU-CVE-2025-8040

## What is CVE-2025-8040?

CVE-2025-8040 is a high-severity memory corruption vulnerability in Mozilla Firefox, published on 22 Jul 2025. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Memory safety bugs present in Firefox ESR 140.0, Thunderbird ESR 140.0, Firefox 140 and Thunderbird 140. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 141, Firefox ESR 140.1, Thunderbird 141, and Thunderbird 140.1.

Weakness: CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2025-8040?

It affects 2 products.


Products: Mozilla Firefox, Mozilla Thunderbird.

## How do I fix CVE-2025-8040?

Upgrade to a fixed version.

## Is CVE-2025-8040 being exploited?

There is no known exploitation of CVE-2025-8040 in the wild and no public exploit code.

## Other vulnerabilities in Mozilla Firefox

- [CVE-2019-11708](https://insights.sbomify.com/CVE-2019-11708/): Mozilla Firefox and Thunderbird Sandbox Escape (critical 10.0, exploited in the wild)
- [CVE-2010-3765](https://insights.sbomify.com/CVE-2010-3765/): Mozilla Multiple Products Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2022-26486](https://insights.sbomify.com/CVE-2022-26486/): Mozilla Firefox Use-After-Free (critical 9.6, exploited in the wild)
- [CVE-2022-26485](https://insights.sbomify.com/CVE-2022-26485/): Mozilla Firefox Use-After-Free (high 8.8, exploited in the wild)
- [CVE-2019-11707](https://insights.sbomify.com/CVE-2019-11707/): Mozilla Firefox and Thunderbird Type Confusion (high 8.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-8040 and fix it if it is affected.

What it is: CVE-2025-8040 is a high-severity memory corruption vulnerability in Mozilla Firefox, published on 22 Jul 2025. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2025-8040 in the wild and no public exploit code.

Affected product: Mozilla Firefox. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-8040/ (Markdown: https://insights.sbomify.com/CVE-2025-8040/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-8040
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-8040
- OSV: https://osv.dev/vulnerability/CVE-2025-8040

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-8040/
Summaries are generated and may contain mistakes; the official description above is the record.