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© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2026-41259

24
FAUCET Score

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.

First published: Apr 23, 2026Last modified: Apr 23, 2026

Impacted Technologies

VendorProductVersion(s)CPE
< 4.3.22CPE matchmatch criteria
cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*
>= 4.4.0, < 4.4.16CPE matchmatch criteria
cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*
>= 4.5.0, < 4.5.9CPE matchmatch criteria
cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 4.0

8.2HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
PRESENT
Privileges Required
NONE
User Interaction
NONE
VS Confidentiality
NONE
VS Integrity
HIGH
VS Availability
NONE
SS Confidentiality
NONE
SS Integrity
NONE
SS Availability
NONE
Exploit Maturity
NOT_DEFINED
CvssVersion
4.0

Exploit Intelligence

EPSS Score
0.21%
Probability of exploitation in next 30 days
EPSS Percentile
11.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0021 is in the 1st percentile among its peer group of 51,553 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (1)

github_advisoryvendor investigatingvia nvd_reference
View patch

References

github.com / mastodon/mastodon/security/advisories/GHSA-5r37-qpwq-2jhh
Vendor Advisory