# CVE-2026-48028

## Summary

- **CVE ID:** CVE-2026-48028
- **Severity:** MEDIUM
- **CVSS Score:** 6.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L)
- **CWE:** CWE-354
- **Published:** Jun 24, 2026
- **Last Modified:** Jun 25, 2026

## 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.

## Affected Products

- mastodon — mastodon (>= 4.5.0-beta.1, < 4.5.10)
- mastodon — mastodon (>= 4.4.0-beta.1, < 4.4.17)
- mastodon — mastodon (< 4.3.23)

## References

- [CNA](https://github.com/mastodon/mastodon/security/advisories/GHSA-53m7-2wrh-q839)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.18%
- **EPSS Percentile:** 7.2

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._