{"apiVersion":"1.0","identifier":"CVE-2026-78551","description":"RansomLook contains multiple weaknesses in its authentication endpoint that allow an unauthenticated remote attacker to enumerate valid usernames, perform unrestricted password-guessing attacks, and potentially exhaust application worker resources. For local authentication, the login implementation previously checked whether a submitted username existed before invoking the password hash verification function. Requests containing a nonexistent username therefore returned significantly faster than requests for valid accounts, for which the computationally expensive password verification routine was executed. A remote attacker could measure these response-time differences to determine which usernames correspond to valid RansomLook accounts. In addition, the /login endpoint did not restrict the number or frequency of failed authentication attempts. An attacker could consequently perform password brute-force, dictionary, password-spraying, or credential-stuffing attacks against known accounts without server-side throttling. For valid usernames, each authentication attempt also invokes the password key-derivation function, which consumes a significant amount of CPU time. A sufficiently high rate of login attempts could therefore occupy the application-s synchronous Gunicorn workers and cause a denial of service affecting the entire application. The issue has been addressed by always performing password verification using a randomly generated dummy password hash when the supplied username does not exist, eliminating the username-dependent timing discrepancy. Failed authentication attempts are additionally rate-limited per client IP address using Valkey/Redis, with five failed attempts within five minutes resulting in a one-hour block. The reverse-proxy configuration was also updated so that the application derives the client address from a trusted X-Forwarded-For value that cannot be overridden by a client-supplied header.","publishedAt":"2026-08-24T20:17:23","lastModifiedAt":"2026-08-26T16:49:18","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-78551","cvssScore":8.8,"cvssVector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/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/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","epssProbability":0.00405,"riskScore":0.91,"affectedProduct":"RansomLook","affectedVersions":"unknown","vulnerabilityType":"Web app","operatingSystems":[],"links":{"self":"https://www.redsauce.net/api/cves/CVE-2026-78551","webPages":{"es":"https://www.redsauce.net/es/cves/CVE-2026-78551","en":"https://www.redsauce.net/en/cves/CVE-2026-78551","fr":"https://www.redsauce.net/fr/cves/CVE-2026-78551","pt":"https://www.redsauce.net/pt/cves/CVE-2026-78551","de":"https://www.redsauce.net/de/cves/CVE-2026-78551","sk":"https://www.redsauce.net/sk/cves/CVE-2026-78551","el":"https://www.redsauce.net/el/cves/CVE-2026-78551"},"source":"https://nvd.nist.gov/vuln/detail/CVE-2026-78551"}}