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VulnerabilityPublished Updated

CVE-2026-93394: Mongo c driver · A flaw in libmongoc's SCRAM authentication implementation caused the client to continue the authentication handshake and transmit the client proof

Affects mongo-c-driverSource GCVE Database

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Authoritative record:CVE-2026-93394· Medium 6.3

Not known to be exploited · CVSS 6.3 Medium.

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.
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

Affected software

ProductAffectedFixed in
Ubuntu 26.04 LTSmongo-c-driverpkg:deb/ubuntu/mongo-c-driver?arch=source&distro=resoluteOther threatsAffected
  • 1.30.4-1ubuntu1 – 2.2.2-1
4 affected builds
Fixed in–
Ubuntu Pro 24.04 LTSmongo-c-driverpkg:deb/ubuntu/mongo-c-driver?arch=source&distro=esm-apps/nobleOther threatsAffected
  • 1.24.3-1 – 1.26.0-1.1ubuntu2+esm1
9 affected builds
Fixed in–
Ubuntu Pro 22.04 LTSmongo-c-driverpkg:deb/ubuntu/mongo-c-driver?arch=source&distro=esm-apps/jammyOther threatsAffected
  • 1.18.0-1 – 1.21.0-1ubuntu0.1~esm1
9 affected builds
Fixed in–
Ubuntu Pro 20.04 LTSmongo-c-driverpkg:deb/ubuntu/mongo-c-driver?arch=source&distro=esm-apps/focalOther threatsAffected
  • 1.15.0-1 – 1.16.1-1ubuntu0.1~esm1
8 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Use of TLS is an effective mitigation, as it prevents man-in-the-middle attackers from intercepting or injecting messages in the authentication handshake. Users should ensure TLS is properly configured and enforced in all deployments using libmongoc SCRAM authentication.

Description

A flaw in libmongoc's SCRAM authentication implementation caused the client to continue the authentication handshake and transmit the client proof even when a nonce mismatch was detected in the server's first message. An unauthorized party with a man-in-the-middle position could exploit this by injecting a crafted server-first-message containing a controlled salt and low iteration count, then capturing the resulting client proof to perform offline password cracking. This vulnerability is mitigated by TLS, which is standard in production deployments.

References

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