# CVE-2026-57962: Denial-of-service via malicious LDAP address-book server

> A malicious LDAP server can cause Thunderbird to crash via memory exhaustion during address-book autocomplete queries.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/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:** 1 Jul 2026
- **Updated:** 1 Jul 2026
- **Also known as:** DEBIAN-CVE-2026-57962, GHSA-qg45-rc8c-9676, UBUNTU-CVE-2026-57962

## What is CVE-2026-57962?

CVE-2026-57962 is a medium-severity denial of service vulnerability in Mozilla Thunderbird, published on 1 Jul 2026. 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

A malicious LDAP server, which a Thunderbird user is configured to query for address-book autocomplete, can stash arbitrarily large amounts of attacker-supplied data into the Thunderbird LDAP client until it crashes due to memory exhaustion. This vulnerability was fixed in Thunderbird 152.0.1 and Thunderbird 140.12.1.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-57962?

It affects 1 product.


Products: Mozilla Thunderbird.

## How do I fix CVE-2026-57962?

Upgrade to a fixed version.

## Is CVE-2026-57962 being exploited?

There is no known exploitation of CVE-2026-57962 in the wild and no public exploit code.

## Other vulnerabilities in Mozilla Thunderbird

- [CVE-2026-92238](https://insights.sbomify.com/CVE-2026-92238/): Ambiguous parsing of mail headers (critical 9.8)
- [CVE-2026-84637](https://insights.sbomify.com/CVE-2026-84637/): Calendar invitation attachments could launch local executables (critical 9.8)
- [CVE-2021-43529](https://insights.sbomify.com/CVE-2021-43529/): Memory corruption in Thunderbird (critical 9.8)
- [CVE-2019-11703](https://insights.sbomify.com/CVE-2019-11703/): Memory corruption in Thunderbird (critical 9.8)
- [CVE-2019-11704](https://insights.sbomify.com/CVE-2019-11704/): Memory corruption in Thunderbird (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-57962 and fix it if it is affected.

What it is: CVE-2026-57962 is a medium-severity denial of service vulnerability in Mozilla Thunderbird, published on 1 Jul 2026. 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-2026-57962 in the wild and no public exploit code.

Affected product: Mozilla Thunderbird. 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-2026-57962/ (Markdown: https://insights.sbomify.com/CVE-2026-57962/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-57962
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-57962
- OSV: https://osv.dev/vulnerability/CVE-2026-57962

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-57962/
Summaries are generated and may contain mistakes; the official description above is the record.