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The vulnerability resides within the `check_apikey()` function inside pyLoad’s web user interface helpers and API core components, which handles API key validation and caching mechanisms. When an API request is processed, the application checks if a valid verification record exists in its internal cache structure. However, this caching mechanism relies solely on the sequential `key_id` parsed directly from the user-supplied API key string rather than verifying the cryptographic secret or hash against the database store on every request. Within the default 300-second cache lifetime window, any subsequent request matching a recently used `key_id` completely skips secret validation. Since `key_id` values are small sequential integers that can be easily enumerated, an unauthenticated attacker who knows or observes a valid `key_id` can forge an arbitrary or empty secret string and successfully bypass authentication entirely, inheriting full user permissions and administrative privileges during the active cache lifespan.
DailyCVE Form:
Platform: pyLoad
Version: <= 0.5.0b3
Vulnerability : Authentication Bypass
Severity: Critical
date: 2026-03-30
Prediction: 2026-04-10
What Undercode Say:
This critical flaw illustrates a classic dangerous pitfall in application architecture: trusting cached authentication metadata without validating the underlying cryptographic secret on every incoming transaction. Because the performance optimization completely bypasses the database key hash check upon a cache hit, attackers can abuse predictable sequential integers to impersonate legitimate sessions effortlessly.
Bash Commands and Codes
Send a legitimate authenticated request to populate the API key cache curl -H "X-API-Key: pl_11<real-43-char-secret>" http://127.0.0.1:8000/api/status Send a forged request using an incorrect secret within the 300-second cache TTL window curl -H "X-API-Key: pl_11xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" http://127.0.0.1:8000/api/status
Exploit: (Educational Purposes!)
An attacker exploits this vulnerability by first monitoring or waiting for a legitimate user or administrative script to execute a valid request against a specific target `key_id` (such as key_id = 1). This action populates the server memory cache via `src/pyload/webui/app/helpers.py` and src/pyload/core/api/__init__.py. Because the cache key is indexed exclusively by the integer `key_id` and lacks any stored key hash verification for subsequent hits, the attacker immediately transmits a crafted or completely forged API key header containing the same target `key_id` but random padding characters for the secret payload. The server evaluates the cache hit, assumes successful authorization without comparing the secret, and returns HTTP 200 OK, granting complete remote access.
Protection:
To secure deployments against this vulnerability, administrators must immediately update pyLoad to the latest patched version where cache validation is strictly enforced. Developers should ensure that cache entries include cryptographic verification hashes of the complete API key, and utilize constant-time comparison functions such as `hmac.compare_digest()` on every authentication check, regardless of whether a cache hit or miss occurs.
Impact:
A successful exploit results in a complete remote authentication bypass, allowing unauthenticated attackers to hijack administrative or user sessions, execute privileged API commands, access sensitive download configurations, and compromise the underlying host environment.
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Sources:
Reported By: github.com
Extra Source Hub:
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