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Description

The MongoDB C Driver's Cyrus SASL integration performs unsafe string copying during username canonicalization, enabling a heap buffer overflow before any authentication or network traffic. This may be triggered by passing untrusted input in the username of a MongoDB URI with authMechanism=GSSAPI.

PUBLISHED Reserved 2026-04-20 | Published 2026-05-06 | Updated 2026-05-06 | Assigner mongodb




HIGH: 8.6CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

HIGH: 7.8CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Problem types

CWE-120 Buffer Copy without Checking Size of Input

Product status

Default status
unaffected

2.1.0 (semver)
affected

References

jira.mongodb.org/browse/CDRIVER-6134

cve.org (CVE-2026-6691)

nvd.nist.gov (CVE-2026-6691)

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