{"id":"CVE-2026-61500","title":"Rejetto HFS < 3.2.1 Session Forgery via Predictable Signing Key","summary":"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 …","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","cwe":["CWE-338"],"vendor":"rejetto","product":"hfs","affected":["hfs >= 3.0.0 < 3.2.1"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"total","timestamp":"2026-07-15T14:14:22.207797Z"},"exploitAvailable":true,"published":"2026-07-13","updated":"2026-10-01","sourceUpdated":"2026-10-01T15:20:09.180Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-61500","references":[{"url":"https://github.com/rejetto/hfs/releases/tag/v3.2.1","label":"hfs v3.2.1 Release Notes"},{"url":"https://www.vulncheck.com/advisories/rejetto-hfs-session-forgery-via-predictable-signing-key"}],"tags":["cve.org","exploit-available"],"epss":0.00857,"epssPercentile":0.56891,"exploits":{"github":1,"githubRepos":["https://github.com/aramosf/CVE-2026-61500"],"checkedAt":"2026-10-01T15:48:52.501Z"},"ingestedAt":"2026-10-01T15:48:17.860Z","slug":"CVE-2026-61500","body":"## Overview\n\nRejetto 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.\n\n## Affected\n\n- `hfs >= 3.0.0 < 3.2.1`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"abyssal","depthScore":66,"depthScoreParts":{"impact":53.9,"likelihood":0.2,"exploitation":12,"ransomware":0},"changes":[]}