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CVE-2025-68475: Fedify has ReDoS Vulnerability in HTML Parsing Regex

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2025-12-22 · updated 2026-09-28
• Weakness: CWE-1333

Description

Fedify is a TypeScript library for building federated server apps powered by ActivityPub. Prior to versions 1.6.13, 1.7.14, 1.8.15, and 1.9.2, a Regular Expression Denial of Service (ReDoS) vulnerability exists in Fedify's document loader. The HTML parsing regex at packages/fedify/src/runtime/docloader.ts:259 contains nested quantifiers that cause catastrophic backtracking when processing maliciously crafted HTML responses. This issue has been patched in versions 1.6.13, 1.7.14, 1.8.15, and 1.9.2.

Affected products

• fedify-dev fedify: before 1.6.13; from 1.7.0 before 1.7.14; from 1.8.1 before 1.8.15; from 1.9.0 before 1.9.2 — fixed in 1.6.13, 1.7.14, 1.8.15, 1.9.2

How to fix

Upgrade to a fixed version: fedify-dev fedify 1.6.13, 1.7.14, 1.8.15, 1.9.2. Check the vendor advisory for mitigations.

References

• https://github.com/fedify-dev/fedify/commit/2bdcb24d7d6d5886e0214ed504b63a6dc5488779
• https://github.com/fedify-dev/fedify/commit/bf2f0783634efed2663d1b187dc55461ee1f987a
• https://github.com/fedify-dev/fedify/releases/tag/1.6.13
• https://github.com/fedify-dev/fedify/releases/tag/1.7.14
• https://github.com/fedify-dev/fedify/releases/tag/1.8.15
• https://github.com/fedify-dev/fedify/releases/tag/1.9.2
• https://github.com/fedify-dev/fedify/security/advisories/GHSA-rchf-xwx2-hm93

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