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TI-2026-26230 Aliases CVE-2026-33869

Mastodon has a denial of service for quote authorization

Priority LOW 21CWE-863Published · Updated

Key facts

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

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-863.

Summary

Mastodon is a free, open-source social network server based on ActivityPub. In versions on the 4.5.x branch prior to 4.5.8 and on the 4.4.x branch prior to 4.4.15, an attacker that knows of a quote before it has reached a server can prevent it from being correctly processed on that server. The vulnerability has been patched in Mastodon 4.5.8 and 4.4.15. Mastodon 4.3 and earlier are not affected because they do not support quotes.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00172 6th percentileScored 2026-11-07
Fix Fixed mastodon (mastodon): 4.5.8, 4.4.15

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
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
mastodonmastodon4.5.0 to before 4.5.8; 4.4.0 to before 4.4.154.5.8, 4.4.15Patch availableCNA
  • mastodon Vendormastodon Affected 4.5.0 to before 4.5.8; 4.4.0 to before 4.4.15 Fixed in 4.5.8, 4.4.15 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*4.4.0 to before 4.4.15; 4.5.0 to before 4.5.8Vulnerablemastodon
  • cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:* Versions 4.4.0 to before 4.4.15; 4.5.0 to before 4.5.8 Vulnerable ·mastodon

Remediation

  • Fix · CNA mastodon (mastodon) Fixed in 4.5.8, 4.4.15

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-33869

References

Advisory 1

  • TI-2022-02004 Improper Restriction of Excessive Authentication Attempts in mastodon/mastodon CVSS 3.1CRITICAL 9.8
  • TI-2025-34613 Mastodon e‑mail throttle misconfiguration allows unlimited email confirmations against unconfirmed emails CVSS 3.1HIGH 7.5
  • 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
See all 41 →

Sources

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