MongoDB C Driver Cyrus SASL Canonicalization Buffer Overflow

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

• mongodb c driver2.1.0 and later · before 2.1.2

Versions reported by the vendor

Affected version ranges reported by the assigning authority (mongodb). Independent of NVD's CPE analysis and usually ahead of it.

• MongoDB Inc. MongoDB C Driver

  • 2.1.0 and later · up to and including 2.1.2affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Other highest-scoring records for the same primary product.

• CVE-2026-93393Heap overflow via oversized decrypted TLS record sequence in Windows Secure Channel stream
  36Monitor
• CVE-2026-96746Heap buffer overflow via mid-scan command list growth in client topology monitoring
  33Monitor
• CVE-2026-84964Heap corruption via OCSP request double free from crafted multi-URL certificate in TLS client
  32Monitor
• CVE-2023-0437MongoDB client C Driver may infinitely loop when validating certain BSON input data
  30Monitor
• CVE-2026-93395Integer Underflow → Heap Out-of-Bounds Read in `bson_new_from_buffer()
  27Monitor
• CVE-2025-12119Bulk write with options may read invalid memory
  27Monitor

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Root cause

When data is copied, the source length is not compared with the size of the destination buffer. Excess data overwrites adjacent memory.

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

1char buf[256];2memcpy(buf, pkt->data, pkt->len);

1char buf[256];2if (pkt->len > sizeof(buf)) {3  return -EINVAL;4}5memcpy(buf, pkt->data, pkt->len);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.