CVE-2026-47746

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.

Overview

State: PUBLISHED
Assigner (CNA): GitHub_M
CVSS severity: HIGH
CVSS score: 8.9 / 10
CVSS vector: 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
Effective score: 8.9 / 10 HIGH source: CNA overview
CWE(s): CWE-367
Reserved: 2026-05-19
Published: 2026-08-03 21:56 UTC
Last updated: 2026-08-03 21:56 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/47xxx/CVE-2026-47746.json
Linked Threat: CVE-2026-47746 — Misskey: JSON-LD signature validation + compaction is vulnerable to timing attacks

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published: 2026-08-03 22:16:49 UTC
NVD last modified: 2026-08-04 15:16:34 UTC
EPSS score: 0.0018 (probability of exploitation in next 30 days)
EPSS percentile: 8.04% vs all CVEs — higher = more likely to be exploited, as of 2026-08-04

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID: EUVD-2026-52488
Assigner: GitHub_M
Published: Aug 3, 2026, 9:56:40 PM
Updated: Aug 4, 2026, 2:11:19 PM
EUVD base score (CVSS 4.0): 8.9 / 10
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
EUVD-reported EPSS: 0.0000
Vendors: misskey-dev
Products: misskey (12.37.0, < 2026.5.4)

ENISA 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.

EUVD references (2)

Affected products (1)

Vendor	Product	Versions	Platforms
misskey-dev	misskey	`>= 12.37.0, < 2026.5.4` (affected)	—

Vendor references (2)

References embedded in the original CVE record by the assigning CNA.

https://github.com/misskey-dev/misskey/security/advisories/GHSA-38jx-423m-g387 x_refsource_CONFIRM
https://github.com/misskey-dev/misskey/releases/tag/2026.5.4 x_refsource_MISC

Web references (0)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

No web references attached yet.

NVD-tagged references (2)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

https://github.com/misskey-dev/misskey/releases/tag/2026.5.4 security-advisories@github.com
https://github.com/misskey-dev/misskey/security/advisories/GHSA-38jx-423m-g387 security-advisories@github.com

Remediations (10)

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

April 2026 Critical Patch Update Released | security - Oracle Blogs

web:blogs.oracle.com

For more information about the Critical Patch Update program, see the security vulnerability remediation practices page located on the Oracle Trust Center.

2026-08-04 20:25 UTC
May 2026 Critical Security Patch Update Released - Oracle Blogs

web:blogs.oracle.com

For more information about the Critical Security Patch Update program, see the security vulnerability remediation practices page located on the Oracle Trust Center.

2026-08-04 20:25 UTC
Security Update Guide - Microsoft

web:portal.msrc.microsoft.com

The Security Update Guide provides information on the latest Microsoft security updates, helping users understand and address potential vulnerabilities effectively.

2026-08-04 20:25 UTC
SAP Security Patch Day - June 2026

web:support.sap.com

SAP security Patch Day Bulletin This post shares the information on security notes that remediate vulnerabilities discovered in SAP products. SAP strongly recommends that the customer visits the support portal and applies patches on priority to protect their SAP landscape. On 9th of June 2026 , SAP security patch day saw the release of 15 new security notes.

2026-08-04 20:25 UTC
SAP Security Patch Day - May 2026

web:support.sap.com

SAP security Patch Day Bulletin This post shares the information on security notes that remediate vulnerabilities discovered in SAP products. SAP strongly recommends that the customer visits the support portal and applies patches on priority to protect their SAP landscape. On 12 th of May 2026 , SAP security patch day saw the release of 15 new security notes.

2026-08-04 20:25 UTC
Addressing Exchange Server May 2026 vulnerability CVE-2026-42897 ...

web:techcommunity.microsoft.com

Hi team, Our organization has successfully implemented the recommended mitigation for CVE - 2026 -42897. However, we are currently experiencing the documented known issues within our environment. Could the Exchange team kindly provide a tentative timeline or ETA for a permanent security update that resolves the underlying vulnerability while addressing these known issues? We would greatly ...

2026-08-04 20:25 UTC
CVE-2026-47746 - vulnerability database | Vulners.com

web:vulners.com

CVE-2026-47746 affects Misskey (open source federated social platform). Affected versions are 12.37. and later, up to but not including 2026.5.4. The issue is a TOCTOU vulnerability in timing attacks during JSON-LD signature validation and the JS...

2026-08-04 20:25 UTC
Oracle Critical Patch Update Advisory - April 2026

web:www.oracle.com

This Critical Patch Update contains 481 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at April 2026 Critical Patch Update: Executive Summary and Analysis.

2026-08-04 20:25 UTC
Oracle Critical Security Patch Update Advisory - May 2026

web:www.oracle.com

This Critical Security Patch Update contains 35 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Security Patch Update and other Oracle Software Security Assurance activities is located at May 2026 Critical Security Patch Update: Executive Summary and Analysis.

2026-08-04 20:25 UTC
July 2026 Patch Tuesday: Largest Patch Tuesday 569 CVEs - Tenable

web:www.tenable.com

Microsoft patched 569 CVEs in July 2026 , the largest Patch Tuesday release in its history. 56 critical CVEs patched including three zero-day vulnerabilities.

2026-08-04 20:25 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-47746.json.

{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "misskey",
          "vendor": "misskey-dev",
          "versions": [
            {
              "status": "affected",
              "version": ">= 12.37.0, < 2026.5.4"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "HIGH",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 8.9,
            "baseSeverity": "HIGH",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "HIGH",
            "userInteraction": "NONE",
            "vectorString": "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "HIGH"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-367",
              "description": "CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-03T21:56:40.198Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/misskey-dev/misskey/security/advisories/GHSA-38jx-423m-g387",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/misskey-dev/misskey/security/advisories/GHSA-38jx-423m-g387"
        },
        {
          "name": "https://github.com/misskey-dev/misskey/releases/tag/2026.5.4",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/misskey-dev/misskey/releases/tag/2026.5.4"
        }
      ],
      "source": {
        "advisory": "GHSA-38jx-423m-g387",
        "discovery": "UNKNOWN"
      },
      "title": "Misskey: JSON-LD signature validation + compaction is vulnerable to timing attacks"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-47746",
    "datePublished": "2026-08-03T21:56:40.198Z",
    "dateReserved": "2026-05-19T22:16:39.504Z",
    "dateUpdated": "2026-08-03T21:56:40.198Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}