Is CVE-2025-11721 in the CISA KEV catalog?

No. CVE-2025-11721 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2025-11721?

CVE-2025-11721 has a CVSS v3 base score of 9.8 (CRITICAL).

What is the EPSS score for CVE-2025-11721?

CVE-2025-11721 has an EPSS score of 0.33% (25th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2025-11721

CRITICAL

9.8

CVSS v3

NVD

Description

Memory safety bug present in Firefox 143 and Thunderbird 143. This bug showed evidence of memory corruption and we presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 144 and Thunderbird 144.

CWE-119Buffer Overflow

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

0.33%probability of exploitation in 30 days

25thpercentile

Low risk: more likely to be exploited than 25% of all known CVEs.

References

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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 2026-04-13.