CVE-2026-84971Persistent client crash loop via undersized FLE2 insert-update ciphertext in decryption path
Updated under an hour ago ()
Does this affect you?
It affects MongoDB libmongocrypt. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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
- 6.5 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- CWE-617
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- mongodb
- NVD analysis
- Analyzed
- Record last updated
- Sep 3, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
MongoDB libmongocrypt mongodb:libmongocrypt (from the name) | from 1.7.0 before 1.20.4 | CNA record |
mongodb libmongocrypt mongodb:libmongocrypt | from 1.7.0 before 1.20.4 | NVD |
References
- https://jira.mongodb.org/browse/MONGOCRYPT-971vendor-advisory, issue-tracking, patch
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.