Vulnerability details
CVE-2026-84971
MongoDB libmongocrypt
Persistent client crash loop via undersized FLE2 insert-update ciphertext in decryption path
CVSS 4.0
7.1High
Official description
Improper handling of an unexpected value size in the decryption path of a client-side encryption library can cause a failed internal check that terminates the process using the library. A party able to place a suitably formed encrypted value where an application will decrypt it, or able to control the responses the application receives, may cause that application to stop running.
CVSS scores
| Score | Version | Source | Vector |
|---|---|---|---|
| 7.1High | 4.0 | CVEProject cvelistV5 (CNA) (mongodb) | 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 |
| 6.5Medium | 3.1 | CVEProject cvelistV5 (CNA) (mongodb) | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
Affected products
| Vendor | Product | Versions | Source |
|---|---|---|---|
| MongoDB | libmongocrypt | 1.7.0 ≤ v < 1.20.4 | CVEProject cvelistV5 (CNA) |
References and advisories
1
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Details
- Published
- 2026-09-03
- Last updated
- 2026-09-03
- State
- Published
- Assigner (CNA)
- mongodb
Exploit prediction (EPSS)
0.25%
Probability of exploitation in 30 days
17.6%
Percentile (among all CVEs)
SSVC assessment (CISA)
- Automatable
- No
- Exploitation
- None
- Technical impact
- Partial
Weaknesses (CWE)
- CWE-617Reachable Assertion