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    CVE-2026-46349

    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 attackers to re-arrange a valid signed JSON-LD activity from a third-party actor to have it processed differently. This vulnerability is fixed in 4.5.10, 4.4.17, and 4.3.23.

    Published:Jun 24, 2026
    Last Modified:Jun 25, 2026
    EPS:Jun 24, 2026
    EPSS Score:0.00162
    CVSS Score:5.3

    Affected Products

    Vendor
    Joinmastodon
    Product
    Mastodon

    Exploits

    No exploit reference

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-463 Padding Oracle Crypto Attack
    CAPEC-475 Signature Spoofing by Improper Validation

    Related CVEs

    CVE-2026-59825 (CVSS 7.4) — Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.4.19 and from 4.5.0 unt…
    CVE-2026-72916 (CVSS 6.3) — Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.4.21, 4.5.14, 4.6.4, an…
    CVE-2026-72915 (CVSS 7.5) — Mastodon is a free, open-source social network server based on ActivityPub. From 4.6.0-beta.1 until 4.6.4 and …
    CVE-2026-72914 (CVSS 7.5) — Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.4.21, 4.5.14, 4.6.4, an…
    CVE-2026-50129 (CVSS 7.5) — Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.11, 4.4.18, and 4.3.2…
    CVE-2026-50128 (CVSS 5.3) — Mastodon is a free, open-source social network server based on ActivityPub. From 4.3.0 until 4.5.11 and 4.4.18…
    CVE-2026-48028 (CVSS 6.5) — Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.10, 4.4.17, and 4.3.2…
    CVE-2026-47389 (CVSS 8.6) — Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.10, 4.4.17, and 4.3.2…
    CVE-2026-46348 (CVSS 8.7) — Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.10, 4.4.17, and 4.3.2…
    CVE-2026-47777 (CVSS 7.5) — Mastodon is a free, open-source social network server based on ActivityPub. In versions there is a missing con…

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High