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Fencer Vulns
high 7.1

CVE-2026-81529 json

Connection-option injection via unescaped settings in the canonical MongoDB URL builder

published 2026-08-27 2 mo ago modified 2026-09-29 40 d ago also EUVD-2026-67213

cvss
7.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 21%
public exploits
0
none known

Summary

Improper neutralization of delimiters in connection-URL construction allows connection-option injection in the MongoDB C# Driver. When an application passes untrusted text into the driver's connection-URL builder and round-trips the builder back into a client configuration, the untrusted text is serialized without neutralizing the URL/option delimiters and is then re-parsed as authoritative connection options. A low-privileged user of such an application can thereby introduce or suppress security-relevant connection settings.

Patch / fix

  • MongoDB C# Driver 3.11.1

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 mo ago

Exploit prediction

0.29% chance of exploitation in the next 30 days, higher than 21% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 7.1 CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N
CNA 3.1 7.1 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N
CNA 4.0 7.1 CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

  • MongoDB C# Driver

Classification

Weakness
  • CWE-88 Improper Neutralization of Argument Delimiters in a Command

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.