CVE-2026-41259: mastodon · Improper Enforcement of Behavioral Workflow
Affects mastodonSource GCVE Database
Not known to be exploited · CVSS 8.2 High · fixed in 4.5.9 : patch mastodon soon.
Data as of 12 Nov 2026, 01:19 UTC
Thin evidence
One scorer or none| CNA (GitHub_M) | CVSS 4.0 | 8.2 |
|---|
- Patch
- Available – fixed in 4.5.9, 4.4.16, 4.3.22
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 23 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 11 Nov 2026.
What to do
Upgrade mastodon to 4.5.9, 4.4.16 or 4.3.22.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| mastodon mastodon | Affected
| Fixed in
|
AI-suggested
This vulnerability is fixed in Mastodon versions 4.3.22, 4.4.16, and 4.5.9. Users and administrators should upgrade to at least these versions to remediate the issue. No additional mitigation steps are indicated by the vendor advisory.
Description
Mastodon versions prior to 4.3.22, 4.4.16, and 4.5.9 contain a vulnerability where the platform's restriction on new user sign-ups by e-mail domain names fails to properly restrict certain characters. These characters can be interpreted differently by some mail servers, leading to improper enforcement of behavioral workflow. This issue is addressed in versions 4.3.22, 4.4.16, and 4.5.9.