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CVE-2026-104817— Misskey: Lack of rate limiting and size restrictions in RSS fetching API

Quick assessment

Affected
misskey-dev misskey
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.

Misskey 是一个开源的联邦式社交媒体平台。从版本 12.112.1 到 2026.7.0，其未认证的 fetch-rss API 缺乏速率限制和响应大小限制，并执行同步 XML 解析。攻击者可以触发无限制的出站 HTTP 请求和同步解析，从而耗尽实例资源、向第三方服务器放大请求，甚至在禁用联邦功能的情况下探测网络可达的服务。该问题已在版本 2026.7.0 中得到修复。

CVSS 8.7 · High EPSS 0.46% · P38

Affected Version Matrix 2

VendorProduct Version RangeStatus
misskey-dev misskey >= 12.0.0, <= 13.14.2 affected
>= 2023.9.0-beta.1, < 2026.7.0 affected
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I. Basic Information for CVE-2026-104817

Vulnerability Information
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Vulnerability Title
Misskey: Lack of rate limiting and size restrictions in RSS fetching API
Source: CVE Program / CVE List V5
Vulnerability Description
Misskey is an open source, federated social media platform. From 12.112.1 until 2026.7.0, the unauthenticated fetch-rss API lacks rate limiting and response-size restrictions and performs synchronous XML parsing. An attacker can trigger unbounded outbound HTTP requests and synchronous parsing, exhausting instance resources, amplifying requests toward third-party servers, or probing network-reachable services even when federation is disabled. This issue is fixed in version 2026.7.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:L/SI:N/SA:L
Source: CVE Program / CVE List V5
Vulnerability Type
不对称的资源消耗(放大攻击)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
misskey-dev misskey >= 12.0.0, <= 13.14.2 -

II. Public POCs for CVE-2026-104817

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III. Intelligence Information for CVE-2026-104817

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Patches & Fixes for CVE-2026-104817 (1)

Vendor Advisories for CVE-2026-104817 (1)

Vendor Pages for CVE-2026-104817 (1)

Same Patch Batch · misskey-dev · 2026-10-13 · 3 CVEs total

CVE-2026-103937 8.7 HIGH Misskey: Denial of service resulting from insufficient cleanup processing during file uplo
CVE-2026-104816 8.5 HIGH Misskey: Cross-site scripting in RSS feed item links

IV. Related Vulnerabilities

Same product: misskey
Same vendor: misskey-dev
Same weakness: CWE-405

V. Comments for CVE-2026-104817

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