Read the docs
TI-2025-34613 Aliases CVE-2025-54879

Mastodon e‑mail throttle misconfiguration allows unlimited email confirmations against unconfirmed emails

Priority HIGH 72CWE-770Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-770.

Summary

Mastodon is a free, open-source social network server based on ActivityPub Mastodon which facilitates LDAP configuration for authentication. In versions 3.1.5 through 4.2.24, 4.3.0 through 4.3.11 and 4.4.0 through 4.4.3, Mastodon's rate-limiting system has a critical configuration error where the email-based throttle for confirmation emails incorrectly checks the password reset path instead of the confirmation path, effectively disabling per-email limits for confirmation requests. This allows attackers to bypass rate limits by rotating IP addresses and send unlimited confirmation emails to any email address, as only a weak IP-based throttle (25 requests per 5 minutes) remains active. The vulnerability enables denial-of-service attacks that can overwhelm mail queues and facilitate user harassment through confirmation email spam. This is fixed in versions 4.2.24, 4.3.11 and 4.4.3.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00613 49th percentileScored 2026-11-07
Fix Fixed mastodon (mastodon): 4.2.24, 4.3.11, 4.4.3

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
mastodonmastodon3.1.5 to before 4.2.24; 4.3.0 to before 4.3.11; 4.4.0 to before 4.4.34.2.24, 4.3.11, 4.4.3Patch availableCNA
  • mastodon Vendormastodon Affected 3.1.5 to before 4.2.24; 4.3.0 to before 4.3.11; 4.4.0 to before 4.4.3 Fixed in 4.2.24, 4.3.11, 4.4.3 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*3.1.5 to before 4.2.24; 4.3.0 to before 4.3.11; 4.4.0 to before 4.4.3Vulnerablemastodon
  • cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:* Versions 3.1.5 to before 4.2.24; 4.3.0 to before 4.3.11; 4.4.0 to before 4.4.3 Vulnerable ·mastodon

Remediation

  • Fix · CNA mastodon (mastodon) Fixed in 4.2.24, 4.3.11, 4.4.3

Timeline

  1. 2026-10-02 Threatist record created from CVE-2025-54879

References

Patch 1

Advisory 1

Other 1

  • TI-2022-02004 Improper Restriction of Excessive Authentication Attempts in mastodon/mastodon CVSS 3.1CRITICAL 9.8
  • TI-2022-22936 Mastodon through 4.0.2 allows attackers to cause a denial of service (large Sidekiq pull… CVSS 3.1HIGH 7.5
  • TI-2023-18301 Mastodon vulnerable to arbitrary file creation through media attachments CVSS 3.1CRITICAL 10.0
  • TI-2023-13359 Mastodon's blind LDAP injection in login allows the attacker to leak arbitrary attributes from LDAP database CVSS 3.1HIGH 7.7
  • TI-2024-16846 External OpenID Connect Account Takeover by E-Mail Change in mastodon CVSS 3.1HIGH 7.4
  • TI-2024-15826 Mastodon Remote user impersonation and takeover CVSS 3.1CRITICAL 9.8
See all 41 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences