CVE-2026-81520
HIGHDescription
A network-reachable client that has not yet authenticated can hold a MongoDB Connector for BI authentication session open indefinitely by beginning a SASL-based login exchange and then declining to complete it. Because the negotiation loop had no overall time bound and the read from the client had no deadline, each such session retains a worker, a client connection slot, and its associated backend database connections until the process is restarted. Repeated use of this behavior can consume the configured connection capacity and prevent legitimate users from establishing new sessions.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Exploit Intelligence
Low risk: more likely to be exploited than 15% of all known CVEs.
References
Related Vulnerabilities
Other CWE-1088 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2024-8062 | High | 7.5 | 0.5% | - | - |
| CVE-2024-8061 | High | 7.5 | 0.5% | - | - |
| CVE-2024-12777 | Medium | 5.9 | 0.5% | - | - |
| CVE-2020-14483 | Medium | 4.3 | 0.4% | - | - |
| CVE-2025-4656 | Low | 3.1 | 0.2% | - | Fix |
Common questions
How do I fix CVE-2026-81520?
No published fix for CVE-2026-81520 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-81520 being actively exploited?
Not that we know of. CVE-2026-81520 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.24% is the estimated probability that it will be exploited in the next 30 days. That is higher than 15% of all scored CVEs.
How severe is CVE-2026-81520?
CVE-2026-81520 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-08-28.