CVE-2026-61500 | THREATINT

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.

PUBLISHED Reserved 2026-07-10 | Published 2026-07-13 | Updated 2026-07-14 | Assigner VulnCheck

CRITICAL: 9.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CRITICAL: 9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Problem types

Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)

Product status

Default status

affected

3.0.0 (semver) before 3.2.1

affected

Credits

Zach Hanley (@hacks_zach) of Horizon3.ai, in collaboration with Claude and Anthropic Research finder

References

github.com/rejetto/hfs/releases/tag/v3.2.1 (hfs v3.2.1 Release Notes) release-notes patch

www.vulncheck.com/...ion-forgery-via-predictable-signing-key third-party-advisory

cve.org (CVE-2026-61500)

nvd.nist.gov (CVE-2026-61500)

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