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CVE-2026-47746— Misskey: JSON-LD signature validation + compaction is vulnerable to timing attacks

Quick assessment

Affected
misskey-dev misskey
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

misskey-dev misskey是misskey-dev公司的一个去中心化的社交网络服务器软件。 misskey-dev misskey 12.37.0版本至2026.5.4之前版本存在竞争条件问题漏洞，该漏洞源于JSON-LD解析上下文未在签名验证和后续处理之间共享，导致TOCTOU缺陷，可能信任不应信任的信息，允许攻击者使欺诈活动被接受为有效，导致完整性丧失。

CVSS 8.9 · High EPSS 0.28% · P19

Affected Version Matrix 1

VendorProduct Version RangeStatus
misskey-dev misskey >= 12.37.0, < 2026.5.4 affected
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I. Basic Information for CVE-2026-47746

Vulnerability Information
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Vulnerability Title
Misskey: JSON-LD signature validation + compaction is vulnerable to timing attacks
Source: CVE Program / CVE List V5
Vulnerability Description
Misskey is an open source, federated social media platform. Versions 12.37.0 and later, but prior to 2026.5.4, are vulnerable to timing attacks during JSON-LD signature validation and the compaction process. Because the JSON-LD parsing context is not shared between signature verification and subsequent processing, the application may trust information that should not be trusted, resulting in a time-of-check to time-of-use (TOCTOU) flaw. This allows an attacker to have fraudulent activities accepted as valid, leading to a loss of integrity. This issue has been fixed in version 2026.5.4.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
检查时间与使用时间(TOCTOU)的竞争条件
Source: CVE Program / CVE List V5
Vulnerability Title
misskey-dev misskey 竞争条件问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
misskey-dev misskey是misskey-dev公司的一个去中心化的社交网络服务器软件。 misskey-dev misskey 12.37.0版本至2026.5.4之前版本存在竞争条件问题漏洞，该漏洞源于JSON-LD解析上下文未在签名验证和后续处理之间共享，导致TOCTOU缺陷，可能信任不应信任的信息，允许攻击者使欺诈活动被接受为有效，导致完整性丧失。
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
misskey-dev misskey >= 12.37.0, < 2026.5.4 -

II. Public POCs for CVE-2026-47746

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 9038 chars
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III. Intelligence Information for CVE-2026-47746

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Vendor Advisories for CVE-2026-47746 (1)

Vendor Pages for CVE-2026-47746 (1)

Same Patch Batch · misskey-dev · 2026-08-03 · 5 CVEs total

CVE-2026-46713 9.2 CRITICAL Misskey: JSON-LD signature validation + compaction may lead to improper activity handling
CVE-2026-48115 6.3 MEDIUM Misskey: Improper Authorization in the Announcements API
CVE-2026-46714 5.1 MEDIUM Misskey: Denial of Service via Uncontrolled Recursion in Theme Compilation
CVE-2026-46712 2.3 LOW Misskey: Lack of proper permission checks in Direct Messaging feature

IV. Related Vulnerabilities

Same product: misskey
Same vendor: misskey-dev
Same weakness: CWE-367

V. Comments for CVE-2026-47746

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