Is CVE-2026-48028 in the CISA KEV catalog?

No. CVE-2026-48028 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-48028?

CVE-2026-48028 has a CVSS v3 base score of 6.5 (MEDIUM).

What is the EPSS score for CVE-2026-48028?

CVE-2026-48028 has an EPSS score of 0.12% (2th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix or mitigate CVE-2026-48028?

No published fix for CVE-2026-48028 has been found yet. Check the linked vendor advisories for guidance as it becomes available.

CVE & CISA-KEV Catalog

CVE-2026-48028

MEDIUM

6.5

CVSS v3

NVD

Description

Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.10, 4.4.17, and 4.3.23, Mastodon's normalization of incoming activities signed with Linked-Data Signatures does not sufficiently protect the activities from a certain class of spoofing, allowing threat actors to remove JSON entries from valid signed activities from a third-party actor. This vulnerability is fixed in 4.5.10, 4.4.17, and 4.3.23.

CWE-354

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.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityLow

AvailabilityLow

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

Exploit Intelligence

0.12%probability of exploitation in 30 days

2ndpercentile

Low risk: more likely to be exploited than 2% of all known CVEs.

References

Other references1

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.