netdisk-fast-download CVE-2026-111612

Exploitation requires that the target instance exposes the /v2/randomAuth endpoint in ParserApi and has donated netdisk credentials stored (the feature that populates the pool of encryptedAuth blobs the endpoint returns) - an instance with no donated credentials has nothing to disclose. No special conditions otherwise: the endpoint is reachable by remote unauthenticated attackers (PR:N/UI:N), and decryption needs no secret because the AES key 'nfd_auth_key2026' is hard-coded in the public source (AuthParamCodec.java:31). The only real limiting factors are network reachability of the service and whether the donation/randomAuth feature is enabled and populated; there is no required authentication, user interaction, or non-default client-side configuration.

All signals point to a genuinely high-confidence, low-barrier confidentiality risk, though the real-world footprint is small. The input CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N/VC:H) describes network-reachable, low-complexity, unauthenticated exploitation with high confidentiality impact and no integrity/availability effect - fully consistent with the description of an unauthenticated attacker repeatedly calling /v2/randomAuth and decrypting the encryptedAuth blob with the hard-coded AES key 'nfd_auth_key2026'. The root cause (CWE-321, use of a hard-coded cryptographic key visible in the public GitHub source at AuthParamCodec.java:31) makes decryption deterministic for anyone, so the 'cryptographic' protection is effectively absent. No EPSS score, CISA KEV listing, or explicit POC/exploit-code flag was provided in the input, so exploitation probability and active-exploitation status cannot be quantified; however, a detailed public technical writeup (the hackmd reference) plus direct source-line references lower the practical barrier considerably even absent packaged exploit code. The signals do not conflict: this is not a high-CVSS-but-low-real-risk case for affected operators - exploitation is trivial where the feature is in use - but the limiting factor is prevalence, not difficulty. Treat as a real priority for any deployment of netdisk-fast-download that stores donated credentials; deprioritize only on the basis of how rarely the product is deployed, not on exploit difficulty.

An attacker on the network identifies an exposed netdisk-fast-download instance (<= 0.4.8) and repeatedly issues unauthenticated GET/POST requests to the /v2/randomAuth endpoint, harvesting encryptedAuth blobs that each represent a different donated account. Because the AES key 'nfd_auth_key2026' is hard-coded in the published source, the attacker decrypts every blob offline to recover other users' cloud-drive cookies, tokens, or passwords. No exploit-code flag is set in the input, but a step-by-step public writeup exists, making reproduction straightforward.