misskey-dev Misskey up to 2026.5.3 JSON-LD Signature Validation toctou

CVSS Meta Temp Score
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CTI Interest Score
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4.1$0-$5k3.29-

Summaryinfo

A vulnerability marked as problematic has been reported in misskey-dev Misskey up to 2026.5.3. This issue affects some unknown processing of the component JSON-LD Signature Validation. The manipulation leads to toctou. This vulnerability is uniquely identified as CVE-2026-47746. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in misskey-dev Misskey up to 2026.5.3. This issue affects an unknown code of the component JSON-LD Signature Validation. The manipulation with an unknown input leads to a toctou vulnerability. Using CWE to declare the problem leads to CWE-367. The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the product to perform invalid actions when the resource is in an unexpected state. Impacted is integrity. The summary by CVE is:

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.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-47746 since 05/20/2026. The exploitation is known to be easy. The attack may be initiated remotely. Neither technical details nor an exploit are publicly available.

Upgrading to version 2026.5.4 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-52488). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

Name

Version

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.3
VulDB Meta Temp Score: 4.1

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Toctou
CWE: CWE-367 / CWE-362
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Misskey 2026.5.4

Timelineinfo

05/20/2026 CVE reserved
08/03/2026 +75 days VulDB entry created
08/04/2026 +0 days Advisory disclosed
08/04/2026 +0 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-47746 (🔒)
GCVE (CVE): GCVE-0-2026-47746
GCVE (VulDB): GCVE-100-385697
EUVD: 🔒

Entryinfo

Created: 08/04/2026 00:16
Updated: 08/04/2026 01:50
Changes: 08/04/2026 00:16 (55), 08/04/2026 01:50 (1)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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