CVE-2026-46349 json
Mastodon: LD-Signature Bypass via JSON-LD Named-Graph Restructuring
published 4mo ago modified 4mo ago also BIT-mastodon-2026-46349 , EUVD-2026-39054 , GHSA-chgx-jx3p-rf73
- cvss
- 5.3
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.2%
- EPSS 0.2% chance of exploitation in 30 days, percentile 9%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- bitnami mastodon 4.5.10
- joinmastodon mastodon 4.5.10
Is CVE-2026-46349 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
- Assessed
- 4mo ago
Exploit prediction
0.20% chance of exploitation in the next 30 days, higher than 9% of all scored CVEs (FIRST EPSS, 2026-11-09).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N |
| OSV | 3.1 | 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| bitnami | mastodon | >=4.5.0, <4.5.10 |
4.5.10 |
Affected products
- mastodon mastodon
Classification
- Weakness
-
- CWE-347 Improper Verification of Cryptographic Signature
References
Sources
- CVE List CVE-2026-46349
- NVD CVE-2026-46349
- OSV BIT-mastodon-2026-46349
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.