CVE-2026-33488: 
PHP vulnerability analysis and mitigation

CVE-2026-33488 is a PGP 2FA bypass vulnerability in the WWBN AVideo LoginControl plugin caused by cryptographically broken 512-bit RSA key generation. The createKeys() function in plugin/LoginControl/pgp/functions.php generates 512-bit RSA keypairs — a key size publicly factorable since 1999 — allowing attackers who obtain a user's public key to factor the modulus, reconstruct the private key, and decrypt any 2FA challenge. Additionally, the generateKeys.json.php and encryptMessage.json.php endpoints lack authentication, enabling unauthenticated denial-of-service via CPU-intensive key generation. All WWBN AVideo versions up to and including 26.0 are affected. The vulnerability was published on March 20, 2026, with a CVSS v3.1 score of 8.1 (High) per Feedly data, or 7.4 (High) per the GitHub Advisory (GitHub Advisory, AVideo Advisory).

The root cause is CWE-326 (Inadequate Encryption Strength): the createKeys() function in plugin/LoginControl/pgp/functions.php (line 26) calls RSA::createKey(512), code copied verbatim from the singpolyma/openpgp-php library's demo code never intended for production use. During login, AVideo generates a uniqid() challenge token, encrypts it with the user's stored 512-bit public key, and requires the user to decrypt and submit the plaintext to verifyChallenge.json.php for verification. Because 512-bit RSA moduli can be factored in hours on commodity hardware using freely available tools (CADO-NFS, msieve, yafu), an attacker who retrieves the target's public key can reconstruct the private key and decrypt any challenge, fully bypassing 2FA. Compounding this, generateKeys.json.php and encryptMessage.json.php perform no authentication checks, exposing CPU-intensive operations to anonymous callers with no rate limiting (GitHub Advisory, AVideo Advisory).

Successful exploitation enables complete 2FA bypass for any account that used the built-in PGP key generator, rendering the second authentication factor entirely ineffective. Combined with credential compromise (via phishing, credential stuffing, or breach reuse), this allows full account takeover of 2FA-protected AVideo accounts, impacting confidentiality and integrity. Separately, the unauthenticated generateKeys.json.php endpoint allows any anonymous user to repeatedly trigger CPU-intensive RSA key generation, degrading server performance and potentially causing denial of service for all deployments with the LoginControl plugin (GitHub Advisory).

A proof-of-concept exploit with detailed step-by-step instructions is publicly available in the GitHub Security Advisory, including specific curl commands and Python code targeting real endpoints such as verifyChallenge.json.php (AVideo Advisory). Feedly classifies the exploit confidence as high, noting it provides sequential exploitation instructions covering RSA modulus extraction, factoring, private key reconstruction, and 2FA challenge submission. There is no current evidence of in-the-wild exploitation, no known threat actor attribution, and the vulnerability is not listed in the CISA KEV catalog. The EPSS score is approximately 0.029–0.044%, placing it in a low percentile for near-term exploitation probability (GitHub Advisory).

1. Reconnaissance: Identify AVideo instances running version 26.0 or earlier with the LoginControl plugin enabled. Confirm the presence of the vulnerable endpoint by sending an unauthenticated GET request to https://target/plugin/LoginControl/pgp/generateKeys.json.php?keyPassword=test&keyName=test&keyEmail=test@test.com — a successful JSON response with PGP key blocks confirms vulnerability.
2. Obtain target's public key: Retrieve the target user's stored PGP public key from the AVideo instance (e.g., via the savePublicKey.json.php endpoint or any exposed user profile data).
3. Extract the RSA modulus: Parse the PGP public key to extract the 512-bit RSA modulus N using GPG or Python (from Crypto.PublicKey import RSA; print(key.n)).
4. Factor the 512-bit modulus: Use a factoring tool such as CADO-NFS (cado-nfs.py <N>) or msieve (msieve -v <N>) to factor N into primes p and q. This typically completes in 2–8 hours on a modern desktop.
5. Reconstruct the private key: Using Python and the pycryptodome library, compute d = inverse(e, (p-1)*(q-1)) with e=65537 and reconstruct the RSA private key via RSA.construct((n, e, d, p, q)).
6. Decrypt the 2FA challenge: Intercept or trigger the login flow for the target account to obtain the PGP-encrypted challenge, then decrypt it using the reconstructed private key.
7. Submit decrypted challenge to bypass 2FA: Submit the plaintext challenge to verifyChallenge.json.php with the target's session cookie: curl -b "session_cookie" "https://target/plugin/LoginControl/pgp/verifyChallenge.json.php" -d "response=<plaintext>". A response of {"error":false} confirms successful 2FA bypass and account access (AVideo Advisory).

• Network: Unauthenticated HTTP GET requests to /plugin/LoginControl/pgp/generateKeys.json.php with parameters keyPassword, keyName, keyEmail from unknown or repeated source IPs; unauthenticated requests to /plugin/LoginControl/pgp/encryptMessage.json.php.
• Network: Repeated or automated POST requests to /plugin/LoginControl/pgp/verifyChallenge.json.php from IPs not associated with the legitimate account holder, particularly following a successful password authentication.
• Logs: Web server access logs showing successful 200 OK responses to generateKeys.json.php or encryptMessage.json.php without an authenticated session cookie.
• Logs: Login audit logs showing 2FA challenge verification (verifyChallenge.json.php) succeeding for accounts from unexpected geographic locations or IP addresses, especially shortly after credential-based login.
• Logs: Elevated CPU usage on the web server correlating with bursts of requests to generateKeys.json.php, indicative of a DoS attempt (AVideo Advisory).

The fix is available in commit 00d979d87f8182095c8150609153a43f834e351e in the WWBN/AVideo repository; users should update to any version newer than 26.0 that includes this patch (AVideo Patch). The patch increases RSA key size from 512 to 2048 bits in functions.php, and adds authentication guards to both generateKeys.json.php and encryptMessage.json.php. Users who previously enabled PGP 2FA using the built-in key generator should disable and re-enroll 2FA after upgrading to regenerate keys at the secure size. As an interim workaround, restrict access to the generateKeys.json.php and encryptMessage.json.php endpoints via WAF rules or web server configuration, and add minimum key size validation (2048-bit minimum) in savePublicKey.json.php to reject previously generated weak keys (GitHub Advisory).