CVE-2024-23837 Overview
CVE-2024-23837 affects LibHTP, a security-aware HTTP protocol parser maintained by the Open Information Security Foundation (OISF). LibHTP is used by Suricata and other network security tools to inspect HTTP traffic. The vulnerability allows remote attackers to send crafted HTTP traffic that triggers excessive processing time of HTTP headers, resulting in a denial-of-service condition. The flaw is categorized under [CWE-770] (Allocation of Resources Without Limits or Throttling). OISF resolved the issue in LibHTP version 0.5.46.
Critical Impact
Remote attackers can degrade or disable network intrusion detection and HTTP inspection capabilities by sending crafted HTTP headers that consume disproportionate CPU resources.
Affected Products
- OISF LibHTP versions prior to 0.5.46
- Fedora 38
- Fedora 39
Discovery Timeline
- 2024-02-26 - CVE-2024-23837 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2024-23837
Vulnerability Analysis
LibHTP parses HTTP requests and responses on behalf of network security monitoring tools. The library lacks adequate throttling when processing HTTP header data. Attackers can craft HTTP traffic containing header structures that force LibHTP into computationally expensive parsing paths. Processing a single crafted request consumes excessive CPU cycles, and sustained traffic exhausts available processing capacity.
The impact extends beyond the parser itself. Because LibHTP is embedded in tools such as Suricata, degraded parser performance reduces the broader network security stack's ability to inspect traffic in real time. Defenders may lose visibility into concurrent malicious activity while the parser is saturated.
Root Cause
The root cause is uncontrolled resource consumption [CWE-770] during HTTP header processing. LibHTP did not bound the work performed when parsing certain header constructs, allowing input complexity to drive parser cost. The maintainers addressed the issue in commit 20ac301d801cdf01b3f021cca08a22a87f477c4a, which introduces processing limits during header parsing.
Attack Vector
The attack vector is network-based and requires no authentication or user interaction. An attacker sends crafted HTTP traffic to any service or sensor where LibHTP processes the traffic stream. In deployments using LibHTP as part of an IDS or IPS, the attacker does not need to be the destination of the traffic — any monitored flow is sufficient. See the OISF security advisory GHSA-f9wf-rrjj-qx8m for additional technical context.
Detection Methods for CVE-2024-23837
Indicators of Compromise
- Sustained high CPU utilization in processes linked against LibHTP, such as suricata, without a corresponding increase in legitimate traffic volume.
- Growing packet capture or flow-processing backlogs in IDS sensors.
- Dropped or unanalyzed HTTP flows reported by Suricata stats.log counters.
- HTTP requests containing unusually large or repetitive header constructs sourced from a small set of remote addresses.
Detection Strategies
- Inspect installed LibHTP versions across sensors and confirm whether they precede 0.5.46.
- Correlate sensor CPU saturation events with inbound HTTP traffic patterns to identify abuse.
- Alert on Suricata events indicating parser errors, truncated transactions, or excessive header counts per request.
Monitoring Recommendations
- Track per-process CPU and memory metrics for HTTP inspection engines and alert on sustained anomalies.
- Monitor Fedora and Debian package advisories for LibHTP updates and ensure timely deployment across affected hosts.
- Baseline normal HTTP header sizes and counts on monitored networks to surface outlier traffic.
How to Mitigate CVE-2024-23837
Immediate Actions Required
- Upgrade LibHTP to version 0.5.46 or later on all systems that link against the library.
- Apply distribution updates for Fedora 38 and Fedora 39 as published in the Fedora package announcements.
- For Debian environments, apply the fix referenced in the Debian LTS announcement.
- Restart Suricata and other dependent services after patching to ensure the updated library is loaded.
Patch Information
The fix is provided in LibHTP 0.5.46 via commit 20ac301d. Vendor advisories are tracked in the OISF GitHub Security Advisory GHSA-f9wf-rrjj-qx8m and the OISF issue tracker. Downstream packages are available through the Fedora package announcement and the corresponding Fedora 39 update.
Workarounds
- Where immediate patching is not possible, place rate limits or upstream filtering in front of HTTP-inspecting sensors to constrain attacker-controlled traffic.
- Disable HTTP parsing rules in Suricata that are not required, reducing the surface processed by LibHTP.
- Distribute traffic across multiple sensor instances to limit the blast radius of a single saturated parser.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
