CVE-2026-61500

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.

CVSS 4.0

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

CVSS 3.1

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

EPSS

1.9% chance of exploitation in the next 30 days; higher than 79% of CVEs (scores of 2026-10-25)

CWE

CWE-338

Published

2026-07-13

Modified

2026-10-24

Record from

the NVD, synced 2026-10-25

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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