CVE-2026-23963— Mastodon missing length limits on list names, filter names, and filter keywords
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I. Basic Information for CVE-2026-23963
Vulnerability Information
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Vulnerability Title
Mastodon missing length limits on list names, filter names, and filter keywords
Source: NVD (National Vulnerability Database)
Vulnerability Description
Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 4.5.5, 4.4.12, and 4.3.18, the server does not enforce a maximum length for the names of lists or filters, or for filter keywords, allowing any user to set an arbitrarily long string as the name or keyword. Any local user can abuse the list or filter fields to cause disproportionate storage and computing resource usage. They can additionally cause their own web interface to be unusable, although they must intentionally do this to themselves or unknowingly approve a malicious API client. Mastodon versions v4.5.5, v4.4.12, v4.3.18 are patched.
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Source: NVD (National Vulnerability Database)
Vulnerability Type
不加限制或调节的资源分配
Source: NVD (National Vulnerability Database)
Vulnerability Title
Mastodon 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Mastodon是Mastodon开源的一款基于ActivityPub的开源社交网络服务器。 Mastodon v4.5.5之前版本、v4.4.12之前版本和v4.3.18之前版本存在安全漏洞，该漏洞源于未强制实施列表、过滤器名称或过滤器关键词的最大长度，可能导致资源滥用。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2026-23963
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Same Patch Batch · mastodon · 2026-01-22 · 4 CVEs total
| CVE-2026-23962 | 7.5 HIGH | Mastodon vulnerable to Denial of Service from a single post (client/server) |
| CVE-2026-23964 | 6.5 MEDIUM | Mastodon has insufficient access control to push notification settings |
| CVE-2026-23961 | 5.3 MEDIUM | Mastodon may allow a remote suspension bypass |
IV. Related Vulnerabilities
Same product: mastodon
- CVE-2026-41259
Mastodon: Insufficient verification of email addresses - CVE-2026-33869
Mastodon has a denial of service for quote authorization - CVE-2026-33868
Mastodon has a GET-Based Open Redirect via '/web/%2F<domain> - CVE-2026-27477
Mastodon has SSRF via unvalidated FASP Provider base_url - CVE-2026-27468
Mastodon may allow unconfirmed FASP to make subscriptions
Same vendor: mastodon
- CVE-2026-41259
Mastodon: Insufficient verification of email addresses - CVE-2026-33869
Mastodon has a denial of service for quote authorization - CVE-2026-33868
Mastodon has a GET-Based Open Redirect via '/web/%2F<domain> - CVE-2026-27477
Mastodon has SSRF via unvalidated FASP Provider base_url - CVE-2026-27468
Mastodon may allow unconfirmed FASP to make subscriptions
Same weakness: CWE-770
- CVE-2026-42294
Argo Workflows: Unauthenticated Memory Exhaustion (DoS) in W - CVE-2026-42189
Russh: Pre-auth DoS via unbounded allocation in keyboard-int - CVE-2026-42793
Atom table exhaustion via attacker-controlled GraphQL SDL na - CVE-2026-44499
ZEBRA: Permanent Block Discovery Halt via Gossip Queue Satur - CVE-2026-44500
ZEBRA: Allocation Amplification in Inbound Network Deseriali
V. Comments for CVE-2026-23963
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