# CVE-2026-11791: 389-ds-base: 389-ds-base: use-after-free in schema reload via attr_syntax_swap_ht()

> An attacker or administrator triggering schema reload during concurrent LDAP traffic can cause a use-after-free, leading to server crash and denial of service.

- **Severity:** Medium 5.0 (`CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Jun 2026
- **Updated:** 30 Jun 2026
- **Also known as:** AZL-90206, DEBIAN-CVE-2026-11791, GHSA-gxp7-cx54-gr2m, UBUNTU-CVE-2026-11791

## What is CVE-2026-11791?

CVE-2026-11791 is a medium-severity use after free vulnerability in Redhat Enterprise Linux, published on 18 Jun 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

A flaw was found in 389 Directory Server. During schema reload, the attr_syntax_swap_ht() function unconditionally frees attribute syntax information nodes, bypassing the refcount-based deferred deletion used elsewhere in the attribute syntax subsystem. If an administrator triggers schema reload while concurrent LDAP query traffic is active, worker threads may access freed memory, resulting in use-after-free or double-free and a denial of service (server crash).

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-11791?

It affects 3 products.


Products: Redhat 389 Directory Server, Redhat Directory Server, Redhat Enterprise Linux.

## How do I fix CVE-2026-11791?

Apply the vendor's patch.

## Is CVE-2026-11791 being exploited?

There is no known exploitation of CVE-2026-11791 in the wild and no public exploit code.

## Other vulnerabilities in Redhat Enterprise Linux

- [CVE-2026-11770](https://insights.sbomify.com/CVE-2026-11770/): 389-ds-base: 389-ds-base: pre-auth ldap filter injection in cleanallruv status check (high 7.5)
- [CVE-2026-15722](https://insights.sbomify.com/CVE-2026-15722/): Memory corruption in Red Hat Directory Server 11.5 E4S for RHEL 8 (high 7.5)
- [CVE-2026-9064](https://insights.sbomify.com/CVE-2026-9064/): Denial of service in Red Hat Directory Server 11.5 E4S for RHEL 8 (high 7.5)
- [CVE-2010-2222](https://insights.sbomify.com/CVE-2010-2222/): Null dereference in Red Hat Directory Server (high 7.5)
- [CVE-2026-11611](https://insights.sbomify.com/CVE-2026-11611/): 389-ds-base: 389-ds-base: content sync plugin unbounded queue growth and race conditions (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-11791 and fix it if it is affected.

What it is: CVE-2026-11791 is a medium-severity use after free vulnerability in Redhat Enterprise Linux, published on 18 Jun 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-11791 in the wild and no public exploit code.

Affected product: Redhat Enterprise Linux. 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-2026-11791/ (Markdown: https://insights.sbomify.com/CVE-2026-11791/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-11791
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-11791
- OSV: https://osv.dev/vulnerability/CVE-2026-11791

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-11791/
Summaries are generated and may contain mistakes; the official description above is the record.