CVE-2026-6691

Publication date 6 May 2026

Last updated 10 July 2026

Ubuntu priority

Cvss 3 Severity Score

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.

Status

Show unmaintained releases

Package	Ubuntu Release	Status
mongo-c-driver	26.04 LTS resolute	Not affected
	25.10 questing	Ignored end of life, was needs-triage
	24.04 LTS noble	Needs evaluation
	22.04 LTS jammy	Needs evaluation
	20.04 LTS focal	Needs evaluation

Severity score breakdown

CVSS version:

Base score 8.6 · High

Base metrics

Parameter	Value
Attack vector	Local
Attack complexity	Low
Attack requirements	None
Privileges required	None
User interaction	None
Vulnerable system - Confidentiality impact	High
Vulnerable system - Integrity impact	High
Vulnerable system - Availability impact	High
Subsequent system - Confidentiality impact	None
Subsequent system - Integrity impact	None
Subsequent system - Availability impact	None

Scores

Parameter	Value
Base score	8.6 · High
Base + Threat score	-
Base + Environmental score	-
Base + Threat + Environmental score	-

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

Base score 7.8 · High

Base metrics

Parameter	Value
Attack vector	Local
Attack complexity	Low
Privileges required	None
User interaction	Required
Scope	Unchanged
Confidentiality impact	High
Integrity impact	High
Availability impact	High

Scores

Parameter	Value
Base score	7.8 · High
Exploitability score	-
Impact score	-

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

CVE-2026-6691

Cvss 3 Severity Score

Description

Status

Severity score breakdown

References

Other references

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