CVE-2026-85664Network attack vector

Unauthenticated service interruption via unbounded HNSW parameters

Published Sep 4, 2026 · Updated Sep 4, 2026

Resource exhaustion in ChromaDB 1.5.9 allows remote attackers to interrupt the server through crafted collection-create requests. Validation accepts unbounded max_neighbors, ef_construction, and ef_search values and passes them into HNSW index processing. No authentication is required by default, and excessive values exhaust server memory when index compaction processes the collection.

CVSS severityUnavailable
Unscored
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in ChromaDB 1.5.9 allows remote attackers to interrupt the server through crafted collection-create requests. Validation accepts unbounded max_neighbors, ef_construction, and ef_search values and passes them into HNSW index processing. No authentication is required by default, and excessive values exhaust server memory when index compaction processes the collection.

The record

CVE
CVE-2026-85664
Published
Sep 4, 2026
Updated
Sep 4, 2026
Vendor
Chroma
Product
ChromaDB
Classifications
T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 4, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=1.5.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Chroma · ChromaDBversion=0 <=1.5.9

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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