SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityDeferred

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.

CRITICAL 9.3EPSS 0.86%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.86%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

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
9.3 CRITICALCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS
0.86% probability · 56th percentile
CISA KEV
Not listed
Weakness
CWE-338
Source
disclosure@vulncheck.com

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.