CVE-2026-114651 — Cross-document data leak via malformed BSON array parsing in reused thread buffer
A memory-handling weakness in the BSON deserialization component of the MongoDB C# Driver may cause data left over from previously processed content to be returned when specially crafted serialized input is parsed. An unauthenticated party able to supply serialized data to an application that maps certain primitive collection types can cause residual bytes from unrelated data processed earlier on the same execution thread to be surfaced as legitimate values. This can result in disclosure of a limited amount of information belonging to other requests or principals of the consuming application. No authentication or special privileges within the application are required.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.4% (30-day exploitation probability)+5
- Technical severity (medium)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Mongodb C Driver).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 6.3 | CVSS 4.0 | Medium | — | — | cna@mongodb.com via NIST National Vulnerability Database |
| 6.3 | CVSS 4.0 | Medium | — | — | mongodb via CVE Program (cve.org) e CISA ADP |
| 4.0 | CVSS 3.1 | Medium | 2.2 | 1.4 | cna@mongodb.com via NIST National Vulnerability Database |
| 4.0 | CVSS 3.1 | Medium | — | — | mongodb via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:N/A:N (score shown at the top: cna@mongodb.com) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
EPSS over time FIRST
Oct 23, 2026 → Oct 27, 2026 · 5 reading(s) · max 0.39%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
- Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
Timeline
What happened to this CVE, newest first.
- 2026
- Source status changed · Received → Awaiting Analysis
- Affected products added · mongodb/c# driver
- Record published
- CVSS changed · 4.0
- Source status changed · → Received
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 2× References added · Oct 22, 2026 – Oct 22, 2026
- 1× Official description updated · Oct 22, 2026 – Oct 22, 2026
References
3 on the record
Elsewhere on this site
Related CVEs (same products)
- Medium CVE-2026-114654 BSON output corruption via out-of-range binary subtype bypassing UUID and OldBinary guards 5d
- Medium CVE-2026-114653 Silent client-side encryption bypass via unescaped field-name regex in CSFLE schema builder 5d
- Medium CVE-2026-114652 Update operator injection via single-element list rewriting in the update builder 5d
- Medium CVE-2026-114647 NoSQL operator injection via unvalidated replacement document in findOneAndReplace 5d
- Medium CVE-2026-114645 Heap overflow via 32-bit length wrap of the URI username in Windows Kerberos auth message wrapping 5d
- High CVE-2026-114648 NoSQL injection via dot and dollar characters in LINQ filter field names and dictionary keys 5d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No fixed version, patch or mitigation documented.
- No CISA SSVC assessment.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-114651 is "Cross-document data leak via malformed BSON array parsing in reused thread buffer", rated Medium. It affects C Driver (Mongodb); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 4.0 describes technical severity. EPSS 0.39% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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