CVE-2024-45338: Parse Functions DoS Vulnerability

CVE-2024-45338 Overview

CVE-2024-45338 is an algorithmic complexity vulnerability affecting the Go programming language's HTML parsing functions. An attacker can craft specially designed input to the Parse functions that would be processed non-linearly with respect to its length, resulting in extremely slow parsing. This could cause a denial of service condition when applications process malicious HTML content.

Critical Impact

Applications using Go's HTML parsing functionality are vulnerable to denial of service attacks through crafted input that triggers non-linear processing time, potentially causing service unavailability.

Affected Products

• Go programming language HTML parsing libraries
• Applications utilizing Go's golang.org/x/net/html package
• NetApp products (as referenced in security advisory)

Discovery Timeline

• 2024-12-18 - CVE CVE-2024-45338 published to NVD
• 2025-02-21 - Last updated in NVD database

Technical Details for CVE-2024-45338

Vulnerability Analysis

This vulnerability is classified under CWE-1333 (Inefficient Regular Expression Complexity), indicating an algorithmic complexity issue in the parsing logic. The Go HTML parser's Parse functions contain code paths where specially crafted input triggers non-linear (potentially quadratic or exponential) processing time relative to input length. This type of algorithmic complexity attack allows relatively small malicious inputs to consume disproportionate CPU resources during parsing operations.

The vulnerability affects network-accessible services that parse HTML content, making it exploitable remotely without authentication. While the confidentiality and integrity of data remain unaffected, the availability impact allows attackers to degrade or deny service to legitimate users.

Root Cause

The root cause lies in inefficient algorithmic handling within the HTML Parse functions. When processing certain input patterns, the parsing algorithm exhibits non-linear time complexity, causing processing time to grow disproportionately as input size increases. This behavior stems from how the parser handles specific HTML constructs or malformed markup, leading to excessive backtracking or repeated operations on the same data.

Attack Vector

The attack vector is network-based, requiring no privileges or user interaction. An attacker can exploit this vulnerability by:

1. Identifying an application endpoint that accepts and parses HTML input
2. Crafting a malicious HTML payload designed to trigger the non-linear parsing behavior
3. Submitting the payload to the target application
4. Causing excessive CPU consumption during parsing, leading to service degradation or denial

The vulnerability can be exploited against any Go application that parses untrusted HTML content using the affected parsing functions. This includes web scrapers, HTML sanitizers, content management systems, and any service that processes user-supplied HTML.

Detection Methods for CVE-2024-45338

Indicators of Compromise

• Unusual CPU spikes during HTML parsing operations
• Extended request processing times for HTML content endpoints
• Service timeouts or unresponsiveness when processing specific HTML payloads
• Memory and CPU exhaustion patterns in application monitoring

Detection Strategies

• Monitor application performance metrics for anomalous CPU usage patterns during HTML parsing
• Implement request timeout monitoring to detect slow parsing operations
• Deploy application-level logging to track parsing duration and identify suspicious inputs
• Use SentinelOne Singularity platform to detect resource exhaustion attacks and abnormal process behavior

Monitoring Recommendations

• Establish baseline metrics for HTML parsing performance to identify deviations
• Configure alerts for CPU usage exceeding normal thresholds during content processing
• Implement request timeout policies with appropriate logging for timeout events
• Monitor Go application runtime metrics including goroutine counts and memory allocation patterns

How to Mitigate CVE-2024-45338

Immediate Actions Required

• Update Go dependencies to include the patched version of the HTML parsing library
• Review the Go.dev Change Log Entry for specific fix details
• Implement input size limits for HTML content before parsing
• Add timeout mechanisms around HTML parsing operations to prevent extended resource consumption

Patch Information

The Go team has released patches to address this vulnerability. The fix is documented in the Go.dev Change Log Entry, with additional technical context available in the Go.dev Issue Tracker Update. Organizations should update their Go modules to incorporate the patched golang.org/x/net/html package. NetApp users should also review the NetApp Security Advisory for product-specific guidance.

For detailed vulnerability tracking information, refer to the Go.dev Vulnerability Report.

Workarounds

• Implement strict input size limits on HTML content accepted for parsing
• Add processing timeouts around HTML parsing operations to abort long-running parses
• Consider using alternative parsing approaches or sandboxed environments for untrusted HTML
• Deploy rate limiting on endpoints that accept HTML input to reduce attack surface

# Example: Update Go dependencies to get the patched version
go get -u golang.org/x/net/html
go mod tidy

# Verify the updated version in go.mod
cat go.mod | grep "golang.org/x/net"