Cross-tenant database retargeting via dot/NUL injection in namespace strings in libmongocrypt (CVE-2026-81523) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-81523

Cross-tenant database retargeting via dot/NUL injection in namespace strings in libmongocrypt

Answer in brief

CVE-2026-81523 records a Unknown severity vulnerability in Cross-tenant database retargeting via dot/NUL injection in namespace strings in libmongocrypt. The current sources do not mark it as known exploited. The current feed maps MongoDB/libmongocrypt (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 27, 2026Updated Aug 27, 2026Source checked Aug 27, 2026First seen by HOL Aug 27, 2026Material review Aug 27, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps MongoDB/libmongocrypt (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
MongoDB/libmongocryptgeneric	>=1.0.0 <1.20.3	1.20.3

Recommended response

Check inventory. Check lockfiles and deployed manifests for MongoDB/libmongocrypt.
Review the reported fix. Update MongoDB/libmongocrypt to 1.20.3 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 27, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 27, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 27, 2026

Sources and claim methodology

GitHub security advisorygithub.com

Upstream source description

A missing input-validation issue in MongoDB libmongocrypt's automatic-encryption context setup allows a caller-supplied database identifier to be accepted without sanitization. The resulting impact is limited to incorrect schema selection, which may lead to limited disclosure or modification of information handled by the application.

Quoted source text, attributed separately from HOL analysis.