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Fencer Vulns
high 7.0

CVE-2026-42462 json

Fedify has an LD-Signature Bypass via JSON-LD Named-Graph Restructuring

published 2026-05-26 5 mo ago modified 2026-09-10 1 mo ago also EUVD-2026-36127 , GHSA-9rfg-v8g9-9367

cvss
7.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 6%
public exploits
0
none known

Summary

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.

Patch / fix

  • npm @fedify/fedify 1.9.11, 1.10.10, 2.0.18, 2.1.14, 2.2.3
  • fedify fedify 1.9.11, 1.10.10, 2.0.18, 2.1.14, 2.2.3

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

0.17% chance of exploitation in the next 30 days, higher than 6% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:L
GitHub 3.1 7.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:L

Affected packages

ecosystem package affected fixed in
npm @fedify/fedify
>=2.2.0, <2.2.3
>=2.1.0, <2.1.14
>=2.0.0, <2.0.18
>=1.10.0, <1.10.10
<1.9.11
2.2.3
2.1.14
2.0.18
1.10.10
1.9.11

Affected products

  • fedify-dev fedify

Classification

Weakness
  • CWE-180 Incorrect Behavior Order: Validate Before Canonicalize
  • CWE-347 Improper Verification of Cryptographic Signature
  • CWE-436 Interpretation Conflict
  • CWE-1289 Improper Validation of Unsafe Equivalence in Input

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.