CVE-2026-41259 json
Mastodon: Insufficient verification of email addresses
published 2026-04-23 6 mo ago modified 2026-09-08 2 mo ago also BIT-mastodon-2026-41259 , EUVD-2026-25282 , GHSA-5r37-qpwq-2jhh
- cvss
- 7.5
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.2%
- EPSS 0.2% chance of exploitation in 30 days, percentile 11%
- public exploits
- 0
- none known
Summary
Mastodon is a free, open-source social network server based on ActivityPub. Prior to v4.5.9, v4.4.16, and v4.3.22, Mastodon allows restricting new user sign-up based on e-mail domain names, and performs basic validation on e-mail addresses, but fails to restrict characters that are interpreted differently by some mailing servers. This vulnerability is fixed in v4.5.9, v4.4.16, and v4.3.22.
Patch / fix
- bitnami mastodon 4.3.22, 4.4.16, 4.5.9
- joinmastodon mastodon 4.3.22, 4.4.16, 4.5.9
CISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
- Assessed
- 6 mo ago
Exploit prediction
0.21% chance of exploitation in the next 30 days, higher than 11% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 8.2 | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N |
| CNA | 4.0 | 8.2 | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
| NVD | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| bitnami | mastodon | <4.3.22 >=4.4.0, <4.4.16 >=4.5.0, <4.5.9 |
4.3.22 4.4.16 4.5.9 |
Affected products
- mastodon mastodon
Classification
- Weakness
-
- CWE-841 Improper Enforcement of Behavioral Workflow
References
-
github.com
/mastodon/mastodon/security/advisories/GHSA-5r37-qpwq-2jhh
vendor-advisory, advisory
-
nvd.nist.gov
/vuln/detail/CVE-2026-41259
web
Sources
- CVE List CVE-2026-41259
- NVD CVE-2026-41259
- OSV BIT-mastodon-2026-41259
Fencer Vulns 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.