CVE-2026-22809: 
JavaScript vulnerability analysis and mitigation

CVE-2026-22809 is a Regular Expression Denial of Service (ReDoS) vulnerability in tarteaucitron.js, a GDPR-compliant cookie banner library. The flaw exists in the handling of the issuu_id parameter and affects all versions prior to 1.29.0. It was discovered by researcher Yasha-ops, disclosed and published on January 13, 2026, with a patch released the same day. The vulnerability carries a CVSS v3.1 base score of 4.4 (Medium) (Github Advisory, GitHub Advisory DB).

The root cause is classified as CWE-1333 (Inefficient Regular Expression Complexity). The vulnerable code in tarteaucitron.services.js applied two unanchored, greedy regular expressions to the attacker-controlled issuu_id parameter: /\d+\/\d+/ and /d=(.*)&u=(.*)/. Because these patterns are not anchored and use greedy .* quantifiers, specially crafted input can trigger catastrophic backtracking, causing excessive CPU consumption. The fix (commit f0bbdac) replaced the patterns with an anchored expression /^\d+\/\d+$/ and removed the second regex entirely, eliminating the backtracking risk (Github Advisory, Fix Commit).

Successful exploitation results solely in an availability impact — no confidentiality or integrity loss is identified. An attacker with high-privilege access who can control the issuu_id parameter can cause CPU exhaustion, degrading application performance or rendering the service temporarily unavailable to legitimate users. The scope is limited to the affected component and does not enable lateral movement or data exfiltration (Github Advisory, GitHub Advisory DB).

There is no known public proof-of-concept exploit and no evidence of in-the-wild exploitation at this time. The vulnerability requires high privileges (local attack vector, PR:H) to exploit, significantly limiting the attacker pool. The EPSS score is approximately 0.012% (0.000120), placing it in a low-risk percentile for near-term exploitation. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog (GitHub Advisory DB, Feedly).

1. Identify target: Locate a web application using tarteaucitron.js versions prior to 1.29.0 with the Issuu service integration enabled and access to configure or supply the issuu_id parameter (requires high-privilege access).
2. Craft malicious input: Construct a specially crafted string for the issuu_id parameter designed to trigger catastrophic backtracking in the unanchored regex patterns /\d+\/\d+/ and /d=(.*)&u=(.*)/ — for example, a long string with repeated partial matches that force the regex engine into exponential backtracking.
3. Submit the payload: Supply the crafted issuu_id value through the application's configuration or input mechanism that passes the value to the vulnerable tarteaucitron.services.js Issuu handler.
4. Trigger CPU exhaustion: The regex engine enters catastrophic backtracking, consuming excessive CPU cycles and causing the application to become unresponsive or unavailable to legitimate users (Github Advisory).

• Logs: Sudden spike in CPU usage correlated with requests or configuration changes involving the Issuu service integration in tarteaucitron.js; application logs showing timeouts or unresponsiveness during regex evaluation.
• Process: Node.js or browser process exhibiting sustained high CPU utilization without corresponding network or I/O activity, particularly when the Issuu embed functionality is invoked.
• File System: Presence of tarteaucitron.js versions older than 1.29.0 (tarteaucitron.services.js containing the unanchored patterns /\d+\/\d+/ or /d=(.*)&u=(.*)/ in the Issuu service handler) (Github Advisory, Fix Commit).

Upgrade tarteaucitron.js to version 1.29.0 or later, which replaces the vulnerable unanchored regex patterns with a properly anchored expression and removes the second greedy pattern entirely. No configuration-based workaround is available; patching is the only remediation. Organizations using the npm package tarteaucitronjs should update via npm update tarteaucitronjs or pin to >=1.29.0 in their package.json (Github Advisory, Fix Commit).