Description
The $regexFindAll expression can be used by an authenticated user who can run aggregation pipeline stages to crash a MongoDB server (mongod). Under certain specific conditions the regex match can start in the middle of a multi-code-unit character, triggering an assertion during query execution.
Affected products
mongodb: mongodb
References1
- jira.mongodb.org/browse/SERVER-127985 Issue TrackingVendor Advisory
Metrics
- CVSS 3.1
-
6.5
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - CVSS 4.0
-
7.1
HIGH
Score source: CNA
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/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:Y/R:A/V:X/RE:X/U:X - EPSS — exploit probability
- 0% percentile: 43 · as of 3 November 2026
- CWE
- CWE-617
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.