Is CVE-2026-12318 in the CISA KEV catalog?

No. CVE-2026-12318 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-12318?

CVE-2026-12318 has a CVSS v3 base score of 7.3 (HIGH).

What is the EPSS score for CVE-2026-12318?

CVE-2026-12318 has an EPSS score of 0.26% (18th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-12318?

Upgrade libnss3 on ubuntu 22.04 to 2:3.98-0ubuntu0.22.04.4 or later. Fixes are available for 5 affected products.

CVE & CISA-KEV Catalog

CVE-2026-12318

HIGH

7.3

CVSS v3

NVD

Description

Incorrect boundary conditions in the Libraries component in NSS. This vulnerability was fixed in Firefox 152 and Thunderbird 152.

CWE-119Buffer Overflow

How to fix

Remediation Available

libnss3Ubuntu

Fixed in:2:3.98-0ubuntu0.22.04.4USN-8481-1

Fixed in:2:3.98-1ubuntu0.2USN-8481-1

Fixed in:2:3.114-1ubuntu0.2USN-8481-1

nssUbuntu

Fixed in:2:3.98-0ubuntu0.22.04.4USN-8481-1

Fixed in:2:3.98-1ubuntu0.2USN-8481-1

Fixed in:2:3.114-1ubuntu0.2USN-8481-1

DeveloperEditionWindows application

Affected:152.0.0Fixed in:152.0.0Mozilla

Mozilla Firefox (en-US)Windows application

Affected:152.0.0Fixed in:152.0.0Mozilla

Mozilla Thunderbird (en-US)Windows application

Affected:152.0.0Fixed in:152.0.0Mozilla

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityLow

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Exploit Intelligence

0.26%probability of exploitation in 30 days

18thpercentile

Low risk: more likely to be exploited than 18% of all known CVEs.

References

Vendor Advisory2

Other references1

bugzilla.mozilla.org

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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 2026-06-17.