# CVE-2022-26386: Information disclosure in Firefox ESR

> Local attackers can read temporary files downloaded by Firefox or Thunderbird on macOS and Linux due to insecure permissions in the shared /tmp directory.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N`)
- **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 Dec 2022
- **Updated:** 15 Apr 2025
- **Also known as:** DEBIAN-CVE-2022-26386, GHSA-8xcq-8jhf-w82h, UBUNTU-CVE-2022-26386

## What is CVE-2022-26386?

CVE-2022-26386 is a medium-severity vulnerability in Mozilla Firefox Esr, published on 22 Dec 2022. 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

Previously Firefox for macOS and Linux would download temporary files to a user-specific directory in <code>/tmp</code>, but this behavior was changed to download them to <code>/tmp</code> where they could be affected by other local users. This behavior was reverted to the original, user-specific directory. <br>*This bug only affects Firefox for macOS and Linux. Other operating systems are unaffected.*. This vulnerability affects Firefox ESR < 91.7 and Thunderbird < 91.7.

Weakness: CWE-377 (DEPRECATED: Insecure Temporary File)

## Which versions are affected by CVE-2022-26386?

It affects 2 products.


Products: Mozilla Firefox Esr, Mozilla Thunderbird.

## How do I fix CVE-2022-26386?

Upgrade to a fixed version.

## Is CVE-2022-26386 being exploited?

There is no known exploitation of CVE-2022-26386 in the wild and no public exploit code.

## Other vulnerabilities in Mozilla Firefox Esr

- [CVE-2021-4127](https://insights.sbomify.com/CVE-2021-4127/): Other in Firefox ESR (critical 9.8)
- [CVE-2023-25746](https://insights.sbomify.com/CVE-2023-25746/): Memory corruption in Firefox ESR (high 8.8)
- [CVE-2021-38495](https://insights.sbomify.com/CVE-2021-38495/): Memory corruption in Firefox ESR (high 8.8)
- [CVE-2020-15669](https://insights.sbomify.com/CVE-2020-15669/): Use after free in Firefox ESR (high 8.8)
- [CVE-2022-38476](https://insights.sbomify.com/CVE-2022-38476/): Use after free in Firefox ESR (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2022-26386 and fix it if it is affected.

What it is: CVE-2022-26386 is a medium-severity vulnerability in Mozilla Firefox Esr, published on 22 Dec 2022. 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-2022-26386 in the wild and no public exploit code.

Affected product: Mozilla Firefox Esr. 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-2022-26386/ (Markdown: https://insights.sbomify.com/CVE-2022-26386/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-26386
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-26386
- OSV: https://osv.dev/vulnerability/CVE-2022-26386

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-26386/
Summaries are generated and may contain mistakes; the official description above is the record.