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Vulnerability record · CVE-2026-42462 · published 10 June 2026

CVE-2026-42462: Improper verification of cryptographic signature vulnerability

Fedify is a TypeScript library for building federated server apps powered by ActivityPub. Prior to versions 1.9.11, 1.10.10, 2.0.18, 2.1.14, and 2.2.3, an attacker can make use of JSON-LD features to restructure a JSON-LD document that would change how Fedify interprets it without changing its Linked Data Signature, allowing them to alter a third-party signed activity they have received. Versions 1.9.11, 1.10.10, 2.0.18, 2.1.14, and 2.2.3 fix the issue.

7.0 CVSS 3.1 High EPSS 0.25% · top 85.5% CWE-180 · CWE-180CWE-347 · Improper verification of cryptographic signature Deferred
7.0CVSS 3.1 base score
0.25%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
2References
23 Jul 2026Last modified by NVD

Description

Fedify is a TypeScript library for building federated server apps powered by ActivityPub. Prior to versions 1.9.11, 1.10.10, 2.0.18, 2.1.14, and 2.2.3, an attacker can make use of JSON-LD features to restructure a JSON-LD document that would change how Fedify interprets it without changing its Linked Data Signature, allowing them to alter a third-party signed activity they have received. Versions 1.9.11, 1.10.10, 2.0.18, 2.1.14, and 2.2.3 fix the issue.

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:L

References

LinkTags
https://github.com/fedify-dev/fedify/releases/tag/2.2.3
https://github.com/fedify-dev/fedify/security/advisories/GHSA-9rfg-v8g9-9367

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Source: NIST National Vulnerability Database (record CVE-2026-42462), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.