Vulnerability in Rejetto Hfs
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.010 (61.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 61st percentile — 61.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.009 · newest: 0.010 · change: +0.001
Affected products
- Rejetto Hfs — versions 3.0.0
Weakness classification (CWE)
Public proof-of-concept exploits
References
- hfs v3.2.1 Release Notes (release-notes, patch)
- www.vulncheck.com/advisories/rejetto-hfs-session-forgery-via-predictable-signin… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-61500?
- CVE-2026-61500 is a critical-severity vulnerability in Rejetto Hfs, classified under Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG). CVSS score: 9.8/10. Published 2026-07-13.
- How severe is CVE-2026-61500?
- Critical severity. CVSS v3 base score is 9.8 out of 10.
- Is CVE-2026-61500 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.