CVE-2026-61500: Rejetto HFS < 3.2.1 Session Forgery via Predictable Signing Key
Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.
Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.
What it is
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.
Description quoted from the CVE record (assigned by VulnCheck, published 2026-07-13).
Weakness: Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)
How it can be exploited
Exploitable over the network with low attack complexity with no special attack requirements needing no privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CISA assessment (SSVC): CISA has no evidence of exploitation. Automatable: yes. Technical impact: total.
Public exploit evidence (Exploit Observer)
Also known as: EUVD-2026-43505, GHSA-xxrm-3f86-v97j
Exploit Observer links 1 piece of public exploit code or detection modules that name this CVE or one of its aliases.
Exploit code and modules (1)
Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.
- Code repository: https://github.com/aramosf/cve-2026-61500
Vulnerability databases and vendor advisories (3)
Catalogue entries, not exploit evidence.
- Vulnerability database or vendor advisory: https://euvd.enisa.europa.eu/enisa/EUVD-2026-43505
- Vulnerability database or vendor advisory: https://github.com/advisories/GHSA-xxrm-3f86-v97j
- Vulnerability database or vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-61500
5 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.
VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.
Live scores
- EPSS
- 0.019
some chance of attack soon - VEDAS
- 0.056
little exploit evidence - On CISA KEV
- Not listed
- Detection rule
- None yet
Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish.
Who is affected
| Product | Affected | Not affected |
|---|---|---|
| rejetto hfs | from 3.0.0 before 3.2.1 | Not stated |
Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.
How to fix it
Fixed versions stated in the CVE record: 3.2.1.
Vendor guidance:
- hfs v3.2.1 Release Notes (release-notes, patch)
How to detect it
There is no open VEDAS detection rule for this bug yet. It is listed on the detection gaps page if CISA has confirmed attacks.
Advisories on this CVE
- Rejetto HFS CVE-2026-61500: an AI-found bug attacked the day after its write-up (full advisory)
- Rejetto HFS session-key auth bypass to RCE (CVE-2026-61500) (1 Oct 2026)
References
Vendor advisories and patches
- hfs v3.2.1 Release Notes (release-notes, patch)
Exploits and technical analysis
- https://www.vulncheck.com/advisories/rejetto-hfs-session-forgery-via-predictable-signing-key (third-party-advisory)
Other databases
Where this comes from
This advisory is generated automatically by VEDAS from: CVE.org record, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.