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
Not known to be exploited · CVSS 6.3 Medium.
Data as of 1 Nov 2026, 22:58 UTC
- 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:NExploitation evidence
Disclosed: evidence found.
CVE published 17 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSmongo-c-driverpkg:deb/ubuntu/mongo-c-driver?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu Pro 24.04 LTSmongo-c-driverpkg:deb/ubuntu/mongo-c-driver?arch=source&distro=esm-apps/nobleOther threats | Affected
| Fixed in– |
Ubuntu Pro 22.04 LTSmongo-c-driverpkg:deb/ubuntu/mongo-c-driver?arch=source&distro=esm-apps/jammyOther threats | Affected
| Fixed in– |
Ubuntu Pro 20.04 LTSmongo-c-driverpkg:deb/ubuntu/mongo-c-driver?arch=source&distro=esm-apps/focalOther threats | Affected
| 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.