Is CVE-2026-48516 in the CISA KEV catalog?

No. CVE-2026-48516 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-48516?

CVE-2026-48516 has a CVSS v3 base score of 7.5 (HIGH).

What is the EPSS score for CVE-2026-48516?

CVE-2026-48516 has an EPSS score of 0.23% (14th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-48516?

Upgrade messagepack to 3.1.7 or later.

CVE & CISA-KEV Catalog

CVE-2026-48516

HIGH

7.5

CVSS v3

NVD

Description

MessagePack for C# is a MessagePack serializer for C#. Prior to 2.5.301 and 3.1.7, InterfaceLookupFormatter<TKey,TElement> constructs an internal Dictionary<TKey, IGrouping<TKey,TElement>> with the default equality comparer instead of the security-aware comparer supplied by options.Security.GetEqualityComparer<TKey>(). This formatter omission allows hash-collision CPU denial of service against ILookup<TKey,TElement> even when the application has opted into the untrusted-data security posture This vulnerability is fixed in 2.5.301 and 3.1.7.

CWE-407

How to fix

Remediation Available

messagepackNVD

Affected:>= 3.0.3, < 3.1.7Fixed in:3.1.7CVE-2026-48516derived from NVD

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

ConfidentialityNone

IntegrityNone

AvailabilityHigh

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

Exploit Intelligence

0.23%probability of exploitation in 30 days

14thpercentile

Low risk: more likely to be exploited than 14% of all known CVEs.

References

Vendor Advisory1

github.com

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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 2026-06-25.