CVE-2026-47746
CVE-2026-47746 is a high-severity vulnerability with a CVSS 4.0 base score of 8.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-367.
Key facts
- Severity: High (CVSS 4.0 base score 8.9)
- EPSS exploit prediction: 0% (8th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-367
- Published:
- Last modified:
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.
Frequently asked questions
- What is CVE-2026-47746?
- 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.
- How severe is CVE-2026-47746?
- CVE-2026-47746 has a CVSS 4.0 base score of 8.9, rated high severity.
- Is CVE-2026-47746 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (8th percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-47746?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- When was CVE-2026-47746 published?
- CVE-2026-47746 was published on 2026-08-03 and last updated on 2026-08-04.
References
- https://github.com/misskey-dev/misskey/releases/tag/2026.5.4
- https://github.com/misskey-dev/misskey/security/advisories/GHSA-38jx-423m-g387
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