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VulnerabilityPublished

CVE-2026-93394: MongoDB C Driver · Incorrect Implementation of Authentication Algorithm

Affects MongoDB C DriverSource CVE Database V5

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Not known to be exploited · CVSS 6.3 Medium : upgrade to 2.3.2 when convenient.

Data as of 1 Nov 2026, 22:58 UTC

CVSS 4.0 base score
6.3Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 25% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 2.3.2
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 17 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 1 Nov 2026.

What to do

Upgrade MongoDB C Driver to 2.3.2.

Affected software

ProductAffectedFixed in
MongoDB Inc.C DriverAffected
  • >=2.0.0 <2.3.2
Fixed in
  • 2.3.2

AI-suggested

Use TLS to protect authentication traffic, as this vulnerability is mitigated by TLS, which is standard in production deployments. Upgrade MongoDB C Driver to version 2.3.2 or later where this issue is fixed. Patch status is confirmed by the affectedVersions field indicating versions <2.3.2 are vulnerable, implying 2.3.2 contains the fix.

Description

CVE-2026-93394 is a vulnerability in MongoDB Inc.'s C Driver (libmongoc) affecting versions from 2.0.0 up to but not including 2.3.2. The flaw lies in the SCRAM authentication implementation, where the client proceeds with the authentication handshake and sends the client proof even if a nonce mismatch is detected in the server's first message. This could allow a man-in-the-middle attacker to inject a crafted server message and capture the client proof, potentially enabling offline password cracking. The vulnerability is mitigated by the use of TLS, which is standard in production environments.

References

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