{"id":"CVE-2026-61500","published":"2026-07-13T17:21:55Z","modified":"2026-10-01T15:20:09Z","title":"Rejetto HFS < 3.2.1 Session Forgery via Predictable Signing Key","vendor":"rejetto","product":"hfs","tier":"core","eol":null,"affectedVersions":[{"vendor":"rejetto","product":"hfs","versions":[">= 3.0.0, < 3.2.1"]}],"description":{"text":"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.","provenance":"source","from":"CVE.org"},"summary":{"text":"The flaw is a predictable session-signing key in Rejetto HFS, affecting versions 3.0.0 through 3.2.0, where the key is derived from the non-cryptographic Math.random() generator whose outputs are exposed to unauthenticated clients during login. An unauthenticated remote attacker needing no user interaction or prior authentication can collect a few login responses, reconstruct the generator's state to recover the signing key, forge an administrator session cookie, and thereby gain full administrative access and remote code execution through the server_code configuration feature.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-29T08:31:48Z"},"cvss":{"score":9.8,"severity":"CRITICAL","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","provenance":"source","from":"CVE.org CNA"},"epss":{"score":0.01908,"percentile":0.79746,"date":"2026-10-30","provenance":"source"},"kev":null,"vulncheckKev":{"dateAdded":"2026-10-01","exploitedFirstSeen":"2026-10-02","ransomware":false,"evidence":[{"url":"https://www.linkedin.com/feed/update/urn:li:activity:7511590230232256513/","date":"2026-10-02"},{"url":"https://www.linkedin.com/posts/ccondon_new-kev-earlier-today-vulnchecks-canary-share-7511574376446590976-NNh3/","date":"2026-10-02"}],"evidenceTotal":2,"provenance":"source"},"exploited":true,"otx":{"pulseCount":0,"pulses":[],"provenance":"machine"},"cwes":[{"id":"CWE-338","name":"Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)"}],"references":[{"url":"https://github.com/rejetto/hfs/releases/tag/v3.2.1","tags":["release-notes","patch"]},{"url":"https://www.vulncheck.com/advisories/rejetto-hfs-session-forgery-via-predictable-signing-key","tags":["third-party-advisory"]}],"techniques":[],"reports":[],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2026-43505","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-43505","exploited":false,"exploitedSince":null,"provenance":"source"},"exploits":[],"exploitSources":{"pocGithub":{"count":1,"skipped":0,"earliest":"2026-09-26","earliestUrl":"https://github.com/aramosf/CVE-2026-61500","repos":[{"name":"aramosf/CVE-2026-61500","url":"https://github.com/aramosf/CVE-2026-61500","stars":0,"created":"2026-09-26"}]},"first":{"date":"2026-09-26","source":"PoC-in-GitHub","url":"https://github.com/aramosf/CVE-2026-61500"},"provenance":"source"},"exploitRefs":[],"flow":[],"timeline":[{"date":"2026-07-13","kind":"published","label":"Published (CVE.org)","url":"https://www.cve.org/CVERecord?id=CVE-2026-61500","provenance":"source"},{"date":"2026-09-26","kind":"exploit-public","label":"First public exploit: PoC-in-GitHub","url":"https://github.com/aramosf/CVE-2026-61500","provenance":"source"},{"date":"2026-10-02","kind":"exploited-reported","label":"Exploitation first reported (VulnCheck KEV evidence)","url":"https://www.linkedin.com/feed/update/urn:li:activity:7511590230232256513/","provenance":"source"}],"speed":{"daysToPublicExploit":75,"firstExploitFrom":"PoC-in-GitHub","daysToKev":null},"priority":{"score":72.8,"factors":[{"name":"In a KEV catalog","points":35.0,"detail":"listed in VulnCheck KEV"},{"name":"Recent KEV listing","points":10.0,"detail":"added 30 days ago"},{"name":"Known ransomware use","points":0.0,"detail":"not known"},{"name":"EPSS percentile","points":15.95,"detail":"percentile 0.7975"},{"name":"Named in threat reports","points":0.0,"detail":"0 reports"},{"name":"Public exploit code","points":5.0,"detail":"1 PoC-in-GitHub repo"},{"name":"Mentioned in OTX pulses","points":0.0,"detail":"0 pulses"},{"name":"CVSS severity","points":6.86,"detail":"base score 9.8"},{"name":"End-of-life product","points":0.0,"detail":"supported or unknown"}]}}