CVE-2026-25235: Pear Pearweb Auth Bypass Vulnerability

CVE-2026-25235 Overview

CVE-2026-25235 is a cryptographic vulnerability affecting PEAR PearWeb, a framework and distribution system for reusable PHP components. Prior to version 1.33.0, the application generates predictable verification hashes that may allow attackers to guess verification tokens and potentially verify election account requests without authorization.

This weakness stems from insecure random number generation (CWE-337: Predictable Seed in Pseudo-Random Number Generator), where the application uses predictable seeds or algorithms when generating cryptographic tokens intended for account verification purposes.

Critical Impact

Attackers may bypass account verification controls by predicting verification tokens, potentially leading to unauthorized access to election-related functionality and account takeover scenarios.

Affected Products

• PEAR PearWeb versions prior to 1.33.0

Discovery Timeline

• 2026-02-03 - CVE CVE-2026-25235 published to NVD
• 2026-02-05 - Last updated in NVD database

Technical Details for CVE-2026-25235

Vulnerability Analysis

This vulnerability is classified as Insecure Random Number Generation (CWE-337), which occurs when a pseudo-random number generator (PRNG) is seeded with a predictable value. In the context of PEAR PearWeb, verification hashes used for election account requests are generated using insufficient entropy, making them susceptible to prediction attacks.

When users initiate account verification requests, the application generates tokens that should be cryptographically random and unpredictable. However, due to the use of weak seeding mechanisms, an attacker with knowledge of the token generation algorithm can potentially compute valid verification hashes without receiving the legitimate verification email.

The network-based attack vector requires no user interaction and can be executed without prior authentication, making it particularly dangerous in multi-user environments where election-related account management is critical.

Root Cause

The root cause lies in the PRNG implementation used to generate verification tokens. The application likely uses predictable seed values such as timestamps, process IDs, or other deterministic data sources that can be guessed or observed by an attacker. This defeats the purpose of verification tokens, which should be impossible to predict without access to the original generation context.

Attack Vector

The attack exploits the network-accessible verification endpoint in PEAR PearWeb. An attacker can:

1. Initiate or observe when a verification request is created
2. Calculate potential verification tokens based on predictable seed values
3. Submit guessed tokens to the verification endpoint
4. Successfully verify accounts without legitimate authorization

The attack requires precise timing knowledge (AT:P in the CVSS vector) but otherwise has low complexity and requires no privileges or user interaction.

The vulnerability manifests in the verification hash generation function. Technical details regarding the specific implementation flaw can be found in the GitHub Security Advisory.

Detection Methods for CVE-2026-25235

Indicators of Compromise

• Multiple failed verification attempts from the same IP address with sequentially predictable tokens
• Successful account verifications occurring without corresponding email delivery logs
• Unusual patterns of verification requests correlating with account creation timestamps
• Verification completions for accounts where the registered email address shows no access to verification links

Detection Strategies

• Monitor verification endpoint logs for brute-force or sequential token submission patterns
• Implement rate limiting on verification endpoints and alert on threshold breaches
• Cross-reference successful verifications with email delivery confirmation logs
• Deploy web application firewall (WAF) rules to detect automated token enumeration attempts

Monitoring Recommendations

• Enable detailed logging for all authentication and verification-related endpoints
• Set up alerts for anomalous verification success rates that deviate from baseline patterns
• Monitor for rapid succession of verification requests that may indicate token guessing
• Track IP addresses associated with multiple verification attempts across different accounts

How to Mitigate CVE-2026-25235

Immediate Actions Required

• Upgrade PEAR PearWeb to version 1.33.0 or later immediately
• Review recent verification logs for signs of unauthorized account verification
• Implement additional rate limiting on verification endpoints as a defense-in-depth measure
• Consider requiring re-verification for accounts verified during the vulnerable period

Patch Information

The vulnerability has been patched in PEAR PearWeb version 1.33.0. The fix addresses the predictable verification hash generation by implementing cryptographically secure random number generation for all verification tokens. Organizations should update to this version or later as soon as possible.

For detailed patch information, refer to the GitHub Security Advisory.

Workarounds

• Implement additional verification steps (multi-factor authentication) for account verification workflows
• Apply strict rate limiting on verification endpoints to slow down potential brute-force attempts
• Temporarily disable automated account verification and switch to manual approval processes
• Monitor and block IP addresses exhibiting suspicious verification patterns

# Example: Rate limiting configuration for verification endpoints
# Add to your web server configuration (Apache example)
<Location "/account/verify">
    # Limit to 5 requests per minute per IP
    SetEnvIf Request_URI "^/account/verify" rate_limit
    LimitRequestBody 1024
</Location>

# For nginx, add to server block:
# limit_req_zone $binary_remote_addr zone=verify:10m rate=5r/m;
# location /account/verify {
#     limit_req zone=verify burst=2 nodelay;
# }