CVE-2026-124959

high

Description

The 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.

References

https://m00dy.sh/notes/when-an-hnsw-index-lies-about-its-capacity

https://github.com/spotify/voyager

https://github.com/nmslib/hnswlib

https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-120081

Details

Source: Mitre, NVD

Published: 2026-11-09

Updated: 2026-11-09

Risk Information

CVSS v2

Base Score: 5.8

Vector: CVSS2#AV:N/AC:M/Au:N/C:N/I:P/A:P

Severity: Medium

CVSS v3

Base Score: 7.1

Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H

Severity: High