Nmaslib Hnswlib and Spotify Voyager HNSW Index Deserialization Heap Out-of-Bounds Write

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-124959
StatePUBLISHED
Assignercertcc
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-11-09 15:17:19 UTC
Updated2026-11-09 15:17:19 UTC
DescriptionThe loadIndex function in nmslib hnswlib and Spotify Voyager does not verify that the element count in a serialized HNSW index is within the stored capacity used to allocate the heap buffer. An attacker can supply a crafted index file with an element count greater than the stored capacity, causing the loader to write beyond the allocated buffer and potentially crash the application when it loads the file.

Risk And Classification

Problem Types: CWE-787 Out-of-bounds Write

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Spotify Voyager affected 2.0.7 2.1.1 custom Not specified
CNA Hnswlib Hnswlib affected 0.5.0 0.9.0 custom Not specified

References

ReferenceSourceLinkTags
m00dy.sh/notes/when-an-hnsw-index-lies-about-its-capacity [email protected] m00dy.sh
github.com/nmslib/hnswlib [email protected] github.com
github.com/spotify/voyager [email protected] github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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