pgvectorscale EUVD-2026-109907

Exploitation requires an authenticated database account (PR:L) that holds CREATE privilege on the vectorscale schema, which lets the attacker pre-create shadow objects shadowing pgvector's vector type or operators; the attacker must then build and query a DiskANN index over crafted values to drive the type confusion. Limiting factors: the attacker must already have a database login and specifically CREATE on the vectorscale schema (not granted to unprivileged users under default/locked-down PostgreSQL 15+ schema permissions); both pgvector and pgvectorscale (before 0.9.1) must be installed; and the AT:P/AC:H metrics indicate a specific attack requirement and non-trivial preconditions must be satisfied rather than a single unconditional request. This is not remote-unauthenticated exploitation against a default install.

The source-provided CVSS 4.0 base score is 7.7 (High) with vector AV:N/AC:H/AT:P/PR:L/UI:N and full VC:H/VI:H/VA:H impact confined to the vulnerable system (SC/SI/SA:N). Several signals temper the raw severity: the vector requires an authenticated low-privileged database user (PR:L), carries high attack complexity (AC:H) and a present attack requirement (AT:P), meaning this is not remote-unauthenticated mass-exploitable code. The practical threat model is an existing, low-trust database principal escalating privileges, disclosing server memory, or crashing the PostgreSQL backend (DoS) - an insider/tenant abuse scenario rather than internet-wide drive-by. No EPSS score is provided in the input, the CVE is not listed in CISA KEV, and no public exploit is identified in the references (the VulnCheck advisory and GitHub source-line links are analysis/patch references, not a working exploit). The vuln.today decision label is 'this_week', which aligns with a real-but-not-emergency priority: patch promptly, but this is not an act_now/emergency situation. Net: a genuine privilege-escalation/memory-corruption flaw that matters most in multi-tenant or shared PostgreSQL deployments where untrusted users hold CREATE on the vectorscale schema; the elevated CVSS is offset by the authentication requirement and high complexity, so it is a legitimate but bounded priority rather than a critical fire.

A low-privileged database user who holds CREATE privilege on the vectorscale schema pre-creates shadow objects that shadow pgvector's vector type or operators, then builds and queries a DiskANN index over crafted values. The resulting type confusion (CWE-843) triggers out-of-bounds reads and writes in the PostgreSQL backend process, letting the attacker disclose server memory, crash the server, or escalate privileges. No public exploit is identified at time of analysis, and the high attack complexity (AC:H) plus attack requirement (AT:P) mean exploitation is not trivial.