TI-2023-18302 Aliases CVE-2023-36461

Mastodon vulnerable to Denial of Service through slow HTTP responses

MEDIUM 41CWE-770Published 2023-07-06 · Updated 2025-02-13

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 · CNA. Fix status from CNA. Impact type from CWE-770.

Summary

Mastodon is a free, open-source social network server based on ActivityPub. When performing outgoing HTTP queries, Mastodon sets a timeout on individual read operations. Prior to versions 3.5.9, 4.0.5, and 4.1.3, a malicious server can indefinitely extend the duration of the response through slowloris-type attacks. This vulnerability can be used to keep all Mastodon workers busy for an extended duration of time, leading to the server becoming unresponsive. Versions 3.5.9, 4.0.5, and 4.1.3 contain a patch for this issue.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.01308 70th percentileScored 2026-11-07

Fix Fixed mastodon (mastodon): 3.5.9, 4.0.5, 4.1.3

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
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

Vendor	Product	Affected versions	Fixed in	Status	Source
mastodon	mastodon	before 3.5.9; 4.0.0 to before 4.0.5; 4.1.0 to before 4.1.3	3.5.9, 4.0.5, 4.1.3	Patch available	CNA

mastodon Vendormastodon Affected before 3.5.9; 4.0.0 to before 4.0.5; 4.1.0 to before 4.1.3 Fixed in 3.5.9, 4.0.5, 4.1.3 Patch available CNA

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:joinmastodon:mastodon::::::::	before 3.5.9; 4.0.0 to before 4.0.5; 4.1.0 to before 4.1.3	Vulnerable	mastodon

cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:* Versions before 3.5.9; 4.0.0 to before 4.0.5; 4.1.0 to before 4.1.3 Vulnerable ·mastodon

Remediation

Fix · CNA mastodon (mastodon) Fixed in 3.5.9, 4.0.5, 4.1.3

Timeline

2026-10-02 Threatist record created from CVE-2023-36461

References

Patch 1

https://github.com/mastodon/mastodon/commit/c5929798bf7e56cc2c79b15bed0c4692ded3dcb6

Advisory 4

Other 1

http://www.openwall.com/lists/oss-security/2023/07/06/7

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