# CVE-2026-86344: Denial of service in Red Hat Directory Server 11

> Unauthenticated attackers can exhaust worker threads in 389-ds-base by sending malformed LDAP sequences, causing a denial of service for all clients.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/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:** Not needed
- **Fix available:** Yes
- **Published:** 1 Oct 2026
- **Updated:** 2 Oct 2026
- **Also known as:** AZL-107951, DEBIAN-CVE-2026-86344, GHSA-62jf-8m49-534w, UBUNTU-CVE-2026-86344

## What is CVE-2026-86344?

CVE-2026-86344 is a high-severity denial of service vulnerability in Red Hat Directory Server 11, published on 1 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A flaw was found in 389-ds-base. An unauthenticated remote attacker can send a complete LDAP operation followed by the first bytes of an incomplete LDAPMessage on the same connection, causing the server to hand that connection to a second worker thread before the first worker's result is flushed. The second worker blocks until nsslapd-ioblocktimeout while holding the connection mutex, preventing delivery of the completed operation's result. Repeating this across a small number of connections proportional to the configured worker-thread pool size exhausts the entire pool under default configuration, denying service to all clients (anonymous and authenticated, plaintext and TLS) for as long as the attacker maintains the connections.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-86344?


## How do I fix CVE-2026-86344?

Apply the vendor's patch.

## Is CVE-2026-86344 being exploited?

There is no known exploitation of CVE-2026-86344 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-86344 and fix it if it is affected.

What it is: CVE-2026-86344 is a high-severity denial of service vulnerability in Red Hat Directory Server 11, published on 1 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-86344 in the wild and no public exploit code.

Affected product: Red Hat Directory Server 11. 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-2026-86344/ (Markdown: https://insights.sbomify.com/CVE-2026-86344/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-86344
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-86344
- OSV: https://osv.dev/vulnerability/CVE-2026-86344

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-86344/
Summaries are generated and may contain mistakes; the official description above is the record.