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CVE-2026-50128— Mastodon: Spoofing of attribution domains

Quick assessment

Affected
mastodon mastodon
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Mastodon是Mastodon组织的一款去中心化社交网络服务器软件。 Mastodon 4.3.0版本至4.4.18之前版本和4.5.0-beta.1版本至4.5.11之前版本存在加密问题漏洞，该漏洞源于attributionDomains JSON-LD术语定义错误，导致Linked Data Signatures无效，攻击者可能绕过签名验证并任意修改属性域值。

CVSS 5.3 · Medium EPSS 0.18% · P7

Affected Version Matrix 2

VendorProduct Version RangeStatus
mastodon mastodon >= 4.5.0-beta.1, < 4.5.11 affected
>= 4.3.0, < 4.4.18 affected
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I. Basic Information for CVE-2026-50128

Vulnerability Information
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Vulnerability Title
Mastodon: Spoofing of attribution domains
Source: CVE Program / CVE List V5
Vulnerability Description
Mastodon is a free, open-source social network server based on ActivityPub. From 4.3.0 until 4.5.11 and 4.4.18, Mastodon has a feature to let websites credit authors of their articles. To prevent false attribution claims, Mastodon uses the attributionDomains JSON-LD term, however, an error in how it is defined makes Linked Data Signatures on the toot:attributionDomains property ineffective. An attacker can arbitrarily modify the attributionDomains value of a legitimately signed Update activity and bypass Mastodon’s signature verification. This vulnerability is fixed in 4.5.11 and 4.4.18.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
完整性检查值验证不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
Mastodon 加密问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Mastodon是Mastodon组织的一款去中心化社交网络服务器软件。 Mastodon 4.3.0版本至4.4.18之前版本和4.5.0-beta.1版本至4.5.11之前版本存在加密问题漏洞，该漏洞源于attributionDomains JSON-LD术语定义错误，导致Linked Data Signatures无效，攻击者可能绕过签名验证并任意修改属性域值。
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

Vendor Product Affected Versions CPE Subscribe
mastodon mastodon >= 4.5.0-beta.1, < 4.5.11 -

II. Public POCs for CVE-2026-50128

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III. Intelligence Information for CVE-2026-50128

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Vendor Advisories for CVE-2026-50128 (1)

Same Patch Batch · mastodon · 2026-06-24 · 6 CVEs total

CVE-2026-47389 8.6 HIGH Mastodon: SSRF protection bypass on older Ruby versions
CVE-2026-50129 7.5 HIGH Mastodon: Persistent anonymous DoS via unhandled NoMethodError in MATH_TRANSFORMER
CVE-2026-48028 6.5 MEDIUM Mastodon: Removal of integrity-protected JSON entries from signed activities
CVE-2026-46349 5.3 MEDIUM Mastodon: LD-Signature Bypass via JSON-LD Named-Graph Restructuring
CVE-2026-46348 Mastodon: SSRF Bypass via IPv6 Unspecified Address (::)

IV. Related Vulnerabilities

Same product: mastodon
Same vendor: mastodon
Same weakness: CWE-354

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