What’s Vulnerable › Vulnerabilities

CVE-2026-61500: Rejetto HFS < 3.2.1 Session Forgery via Predictable Signing Key

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-13 · updated 2026-10-24
• Weakness: CWE-338

Description

Rejetto HFS 3.0.0 through 3.2.0 derives its session-cookie signing key from the non-cryptographic Math.random() generator and discloses outputs of the same generator to unauthenticated clients during login. A remote attacker can collect a small number of login responses, reconstruct the generator's state, recover the signing key, and forge a valid administrator session cookie, leading to full administrative access and remote code execution via the server_code configuration feature.

Affected products

• rejetto hfs: from 3.0.0 before 3.2.1 — fixed in 3.2.1

How to fix

Upgrade to a fixed version: rejetto hfs 3.2.1. Check the vendor advisory for mitigations.

References

• https://github.com/rejetto/hfs/releases/tag/v3.2.1
• https://www.vulncheck.com/advisories/rejetto-hfs-session-forgery-via-predictable-signing-key

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