CVE-2026-84971: Persistent client crash loop via undersized FLE2 insert-update ciphertext in decryption path
MongoDB · libmongocrypt
Vendor fix available · Affected: MongoDB libmongocrypt · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 17% of scored CVEs
DescriptionCVE.org
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.
Affected products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- MongoDB · libmongocryptfrom 1.7.0 before 1.20.4
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Unlikely (under 1%). EPSS under 1%, or no score yet.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Vendor
- MongoDB
- Published
- September 2026
CoverageNo articles yet
No CyberSIXT article names CVE-2026-84971 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.