How severe is CVE-2026-18703?

CVE-2026-18703 has a CVSS 3.x base score of 4.2, rated medium severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-18703 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (3rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-18703?

CVE-2026-18703 primarily affects Mongodb. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-18703?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2026-18703 published?

CVE-2026-18703 was published on 2026-08-11 and last updated on 2026-09-16.

CVE-2026-18703

CVE-2026-18703 is a medium-severity vulnerability in Mongodb with a CVSS 3.x base score of 4.2. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-863.

Key facts

Severity: Medium (CVSS 3.x base score 4.2)
CVSS v4: 2.3
EPSS exploit prediction: 0% (3rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-863
Affected product: Mongodb
Published: 2026-08-11
Last modified: 2026-09-16

Description

An issue in MongoDB Server could allow a party with a valid client certificate and a corresponding user account to authenticate using a certificate-based authentication method, even when an administrator has configured the server to restrict authentication to other mechanisms. This could allow authentication through a method the administrator intended to disable.

Frequently asked questions

What is CVE-2026-18703?: An issue in MongoDB Server could allow a party with a valid client certificate and a corresponding user account to authenticate using a certificate-based authentication method, even when an administrator has configured the server to restrict authentication to other mechanisms. This could allow authentication through a method the administrator intended to disable.
How severe is CVE-2026-18703?: CVE-2026-18703 has a CVSS 3.x base score of 4.2, rated medium severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-18703 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (3rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-18703?: CVE-2026-18703 primarily affects Mongodb. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-18703?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-18703 published?: CVE-2026-18703 was published on 2026-08-11 and last updated on 2026-09-16.

References

https://jira.mongodb.org/browse/SERVER-127863

Affected products (4)

cpe:2.3:a:mongodb:mongodb:*:*:*:*:*:*:*:*
cpe:2.3:a:mongodb:mongodb:9.0.0:alpha0:*:*:-:-:*:*
cpe:2.3:a:mongodb:mongodb:9.0.0:alpha1:*:*:-:-:*:*
cpe:2.3:a:mongodb:mongodb:9.1.0:alpha0:*:*:-:-:*:*

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