# CVE-2026-85664: Chroma 1.5.9 Unbounded HNSW Index Parameters Memory Exhaustion

> Unauthenticated attackers can cause denial of service in Chroma vector database by supplying unbounded HNSW index parameters that exhaust server memory.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 4 Sep 2026
- **Updated:** 10 Sep 2026
- **Also known as:** GHSA-3q9g-fh5w-hp67

## What is CVE-2026-85664?

CVE-2026-85664 is a high-severity denial of service vulnerability in chroma-core chroma, published on 4 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Chroma 1.5.9 fails to validate maximum bounds on HNSW index parameters max_neighbors, ef_construction, and ef_search in collection-create requests. Unauthenticated attackers can supply arbitrarily large parameter values to exhaust server memory and cause denial of service during index compaction.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2026-85664?


## How do I fix CVE-2026-85664?

No fix has been published for CVE-2026-85664 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-85664 being exploited?

There is no known exploitation of CVE-2026-85664 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-85664 and fix it if it is affected.

What it is: CVE-2026-85664 is a high-severity denial of service vulnerability in chroma-core chroma, published on 4 Sep 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-2026-85664 in the wild and no public exploit code.

Affected product: chroma-core chroma. 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-2026-85664/ (Markdown: https://insights.sbomify.com/CVE-2026-85664/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-85664
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-85664
- OSV: https://osv.dev/vulnerability/CVE-2026-85664

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-85664/
Summaries are generated and may contain mistakes; the official description above is the record.