CVE-2026-93761 — Denial of service via unbounded regex matching in Mongoid's in-memory query matcher
An inefficient regular expression complexity issue in the in-memory query evaluation component of the Mongoid library may allow an unauthenticated party to cause excessive processing within an embedding application process. Applications that place user-supplied text into a pattern-matching query condition on an embedded association may become unresponsive.
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
- Technical severity (high)+6
- Automatable exploitation (SSVC)+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.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
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 Mongoid).
- 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 (denial of service), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Mongodb | Mongoid | ≥ 8.0.0 and < 8.0.13≥ 8.1.0 and < 8.1.13≥ 9.0.0 and < 9.0.12version 9.1.0 | Vulnerable | NIST National Vulnerability Database |
| Mongodb | Mongoid |
≥ 7.2.0 and ≤ 7.2.6≥ 7.3.0 and ≤ 7.3.5≥ 7.4.0 and ≤ 7.4.3≥ 7.5.0 and ≤ 7.5.4≥ 7.6.0 and ≤ 7.6.1≥ 8.0.0 and ≤ 8.0.12≥ 8.1.0 and ≤ 8.1.12≥ 9.0.0 and ≤ 9.0.11 and 1 moreversion 9.1.0 |
Vulnerable | CVE Program (cve.org) e CISA ADP |
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 |
|---|---|---|---|---|---|
| 8.7 | CVSS 4.0 | High | — | — | cna@mongodb.com via NIST National Vulnerability Database |
| 8.7 | CVSS 4.0 | High | — | — | mongodb via CVE Program (cve.org) e CISA ADP |
| 7.5 | CVSS 3.1 | High | 3.9 | 3.6 | cna@mongodb.com via NIST National Vulnerability Database |
| 7.5 | CVSS 3.1 | High | — | — | mongodb via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (score shown at the top: cna@mongodb.com) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
CWE-1333 · Inefficient Regular Expression Complexity (ReDoS)
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).
- Track CPU/memory spikes and availability drops correlated with request patterns.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · mongodb inc./mongoid
- SSVC assessment updated
- Record published
- CVSS changed · 7.5
- Source status changed · → Analyzed
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 15, 2026 – Oct 15, 2026
References
1 on the record
Elsewhere on this site
Related CVEs (same products)
- Critical CVE-2026-93762 Data deletion and attribute disclosure via field-name method injection in in-memory queries 27d
- Medium CVE-2026-93763 Silent plaintext persistence via unresolved callable database name in encryption schema map 27d
- Medium CVE-2026-93764 Plaintext storage of encrypted fields via skipped embedded models in encryption schema generation 27d
- High CVE-2026-93759 Server-side JavaScript injection via string query criteria bypassing the strict operator allowlist 27d
- High CVE-2026-93760 NoSQL injection of JavaScript-executing query operators via unsafe-by-default operator guard 27d
- High CVE-2026-93758 Cross-principal document update, theft, and deletion via unvalidated id in nested attributes 27d
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 FIRST EPSS score.
- No fixed version, patch or mitigation documented.
- 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-2026-93761 is "Denial of service via unbounded regex matching in Mongoid's in-memory query matcher", rated High. It affects Mongoid (Mongodb); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.5 describes technical severity. 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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