Misskey: JSON-LD signature validation + compaction is vulnerable to timing attacks
Summary
| CVE | CVE-2026-47746 |
|---|---|
| State | PUBLISHED |
| Assigner | GitHub_M |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-08-03 22:16:49 UTC |
| Updated | 2026-08-04 15:16:34 UTC |
| 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. |
Risk And Classification
Primary CVSS: v4.0 8.9 HIGH from [email protected]
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS: 0.001820000 probability, percentile 0.079800000 (date 2026-08-08)
Problem Types: CWE-367 | CWE-367 CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 8.9 | HIGH | 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/E:X/C... |
| 4.0 | CNA | DECLARED | 8.9 | HIGH | 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 |
CVSS v4.0 Breakdown
Attack Vector
NetworkAttack Complexity
HighAttack Requirements
NonePrivileges Required
NoneUser Interaction
NoneConfidentiality
NoneIntegrity
HighAvailability
NoneSub Conf.
NoneSub Integrity
HighSub Availability
NoneCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Misskey-dev | Misskey | affected >= 12.37.0, < 2026.5.4 | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/misskey-dev/misskey/releases/tag/2026.5.4 | [email protected] | github.com | |
| github.com/misskey-dev/misskey/security/advisories/GHSA-38jx-423m-g387 | [email protected] | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.