CVE-2026-78551
RansomLook Login Endpoint Allows Timing-Based Username Enumeration and Unthrottled Authentication Attempts
Published Aug 24, 2026
CVSS 4.0 · 8.8 High
EPSS < 1%
KEV · Not listed
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.
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.
Affected Products
-
CVE record
-
NVD configurations
No data
-
Red Hat packages
No data
-
OpenCVE enrichment
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| ransomlook | ransomlook | unaffected |
|
No data.
No data.
| Vendor | Product | Versions | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Ransomlook | Ransomlook |
|
Remediation
Tracking
Advisories
Metrics
Attack Vector Network
Attack Complexity Low
Privileges Required None
Attack Requirements None
User Interaction None
Vulnerable System Confidentiality Impact Low
Vulnerable System Integrity Impact None
Vulnerable System Availability Impact High
Subsequent System Confidentiality Impact None
Subsequent System Integrity Impact None
Subsequent System Availability Impact None
No CVSS v3.1
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.649% probability within 30 days)
Exploitation none
Automatable yes
Technical Impact partial
References
History
Aug 24, 2026 9:30 PM
Scoring metrics updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
Aug 24, 2026 8:45 PM
First appearance in the feed. Affected vendors updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Ransomlook
Ransomlook ransomlook |
|
| Vendors & Products |
Ransomlook
Ransomlook ransomlook |
Aug 24, 2026 7:45 PM
Description updated. Title updated. Weaknesses updated. Added references. Scoring metrics updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | RansomLook Login Endpoint Allows Timing-Based Username Enumeration and Unthrottled Authentication Attempts | |
| Weaknesses | CWE-307 CWE-400 |
|
| References |
| |
| Metrics |
cvssV4_0
|
