CVE-2026-22863: Deno Information Disclosure Vulnerability

CVE-2026-22863 Overview

CVE-2026-22863 is a critical cryptographic vulnerability affecting Deno, a JavaScript, TypeScript, and WebAssembly runtime. The vulnerability exists in the node:crypto module, which fails to properly finalize cipher operations. This flaw allows attackers to perform unlimited encryption operations, potentially enabling brute force attacks or more sophisticated cryptanalysis techniques aimed at extracting server secrets.

Critical Impact

Attackers can exploit the improper cipher finalization to conduct unlimited encryption attempts, potentially compromising server secrets through brute force or refined cryptographic attacks.

Affected Products

• Deno versions prior to 2.6.0
• Applications using node:crypto module in vulnerable Deno versions
• Server-side Deno applications performing cryptographic operations

Discovery Timeline

• 2026-01-15 - CVE CVE-2026-22863 published to NVD
• 2026-01-21 - Last updated in NVD database

Technical Details for CVE-2026-22863

Vulnerability Analysis

This vulnerability stems from improper handling of cipher finalization in Deno's node:crypto compatibility layer. When cryptographic cipher operations are not properly finalized, the system fails to enforce expected limitations on encryption operations. This creates a scenario where an attacker can repeatedly invoke encryption functions without the normal constraints that would otherwise prevent abuse.

The missing required cryptographic step (CWE-325) means that authenticated encryption modes may not properly validate or complete their cryptographic transformations. In practical terms, this allows adversaries to gather an unlimited number of ciphertext samples, which is particularly dangerous when combined with known-plaintext or chosen-plaintext attack scenarios.

Root Cause

The root cause of CVE-2026-22863 is the failure to call the cipher finalization routine in the node:crypto implementation. Cipher finalization is a critical step in symmetric encryption that ensures all buffered data is processed, padding is applied correctly, and authentication tags (in authenticated encryption modes) are properly generated or verified. Without finalization, the cipher may remain in an incomplete state, allowing continued use beyond its intended lifecycle.

Attack Vector

The attack vector is network-based, requiring no authentication or user interaction. An attacker with network access to a vulnerable Deno application can exploit this vulnerability by:

1. Sending crafted requests that trigger cryptographic operations
2. Observing the responses or timing characteristics
3. Repeating this process indefinitely due to the lack of cipher finalization
4. Accumulating enough encrypted samples to perform statistical analysis or brute force attacks against server secrets

The vulnerability is particularly concerning for applications that use session encryption, token generation, or other security-sensitive cryptographic operations.

Detection Methods for CVE-2026-22863

Indicators of Compromise

• Unusual spikes in cryptographic operation requests to Deno applications
• High volume of requests to endpoints performing encryption operations
• Anomalous patterns in encrypted response data suggesting enumeration attempts
• Increased memory usage in Deno processes due to unfinalized cipher contexts

Detection Strategies

• Monitor application logs for excessive encryption-related API calls from single sources
• Implement rate limiting on endpoints that perform cryptographic operations
• Review Deno application dependencies and runtime version to identify vulnerable installations
• Use SentinelOne Singularity Platform to detect anomalous process behavior in Deno runtime environments

Monitoring Recommendations

• Enable verbose logging for node:crypto module operations in Deno applications
• Set up alerts for unusual encryption request patterns or volumes
• Monitor network traffic for repeated similar requests targeting crypto endpoints
• Deploy runtime application self-protection (RASP) to detect cryptographic abuse patterns

How to Mitigate CVE-2026-22863

Immediate Actions Required

• Upgrade Deno to version 2.6.0 or later immediately
• Audit all applications using node:crypto module for potential exposure
• Implement rate limiting on cryptographic operations as a defense-in-depth measure
• Review server secrets that may have been exposed and rotate credentials if exploitation is suspected

Patch Information

Deno has addressed this vulnerability in version 2.6.0. The fix ensures proper cipher finalization in the node:crypto compatibility layer, preventing unlimited encryption operations. Organizations should upgrade to 2.6.0 or later to remediate this vulnerability.

For detailed patch information, refer to the GitHub Release v2.6.0 and the GitHub Security Advisory GHSA-5379.

Workarounds

• Implement application-level rate limiting on cryptographic operations until patching is complete
• Add request throttling at the network or load balancer level for endpoints performing encryption
• Consider temporarily disabling or restricting access to non-essential cryptographic features
• Deploy Web Application Firewall (WAF) rules to detect and block suspicious request patterns

# Upgrade Deno to patched version
deno upgrade --version 2.6.0

# Verify installed version
deno --version