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CVE-2026-54465 is a memory exhaustion vulnerability in the websocket-driver library, a WebSocket protocol handler with pluggable I/O. The flaw exists in the HTTP header parsing logic for versions prior to 0.8.1. When the library is used to implement a WebSocket server directly on top of a TCP server (via WebSocket::Driver.server()) rather than through an HTTP server framework, or when it complements a WebSocket client, a remote peer can exhaust server memory by sending an HTTP request or response containing an unbounded, never-ending list of headers. The parser processes each header line sequentially, allocating memory for every header without enforcing any limit on the total number or cumulative size of headers. Because the header processing loop lacks bounds checking, a single malicious connection can force the receiving process to allocate an arbitrarily large amount of memory, leading to Out‑of‑Memory (OOM) conditions. This vulnerability is classified under CWE-770 (Allocation of Resources Without Limits or Throttling) and aligns with MITRE ATT&CK technique T1499.004 for resource exhaustion targeting memory. The attack requires no authentication and can be initiated remotely over the network, making it particularly dangerous for publicly exposed WebSocket servers. The impact is a denial of service that can crash the application, destabilize the host system, or degrade performance for legitimate users. The vulnerability was discovered and reported by Pranjali Thakur of the DepthFirst Security Research Team. The fix, released in version 0.8.1, caps the total size of HTTP request/response lines and headers accepted by the parser to 32 KB, effectively preventing unbounded memory allocation. No workarounds are available; upgrading to the patched version is the only complete mitigation.
DailyCVE Form:
Platform: websocket-driver library
Version: < 0.8.1
Vulnerability: Unbounded header memory allocation
Severity: Medium (CVSS 6.3)
date: 2026-07-17
Prediction: 2026-06-04 (patched)
What Undercode Say:
Analytics:
- CVSS v4.0 Base Score: 6.3 MEDIUM
- Attack Vector: Network (remotely exploitable)
- Attack Complexity: Low
- Privileges Required: None
- User Interaction: None
- EPSS (Exploit Probability): 0.32% (low)
- Affected Versions: all prior to 0.8.1
- Patched Version: 0.8.1 (limits total header size to 32 KB)
- Discovery: Pranjali Thakur, DepthFirst Security Research Team
- Weakness: CWE-770 (Uncontrolled Resource Allocation)
Bash Commands & Codes:
Check installed version of websocket-driver (Ruby)
gem list websocket-driver
For Ruby projects, inspect Gemfile.lock
grep websocket-driver Gemfile.lock
Check version in package.json (Node.js)
grep websocket-driver package.json
For Debian/Ubuntu systems with ruby-websocket-driver package
dpkg -l | grep websocket-driver
Upgrade to patched version (Ruby)
gem update websocket-driver -v 0.8.1
Or in Gemfile
bundle update websocket-driver
For npm (if using the Node.js port)
npm update websocket-driver
Verify upgrade
gem list websocket-driver | grep 0.8.1
Memory monitoring during potential exploitation
while true; do ps aux | grep [bash]ebsocket | awk ‘{print $2, $4, $6}’; sleep 5; done
Simulate a malicious header flood using netcat (proof-of-concept)
printf “GET / HTTP/1.1\r\n” > headers.txt
for i in {1..100000}; do echo “X-Header-$i: value” >> headers.txt; done
echo -e “\r\n” >> headers.txt
nc -v target_host target_port < headers.txt
Exploit:
An attacker establishes a single TCP connection to the WebSocket server and sends a crafted HTTP Upgrade request with an extremely large number of headers (e.g., thousands or millions). The websocket-driver parser processes each header line, allocating memory for every header string without any limit on total header count or cumulative size. As the connection remains open and headers are streamed, memory consumption grows unbounded until the process exhausts available RAM, triggering an OOM kill or application crash. The attack requires no special privileges and can be executed with simple tools like netcat or custom scripts. Because the vulnerability exists before the WebSocket handshake completes, even endpoints that eventually reject malformed requests are susceptible to memory exhaustion during parsing.
Protection:
- Immediately upgrade to websocket-driver version 0.8.1 or later, which enforces a hard 32 KB limit on the total size of HTTP request/response lines and headers.
- If immediate upgrade is not possible, deploy a reverse proxy (e.g., nginx, HAProxy) in front of the WebSocket server to validate and limit incoming HTTP header sizes before they reach the vulnerable library.
- Implement connection-level resource limits (e.g., max concurrent connections per client, timeout policies) to reduce the blast radius of a single malicious connection.
- Monitor memory usage of WebSocket server processes and set up alerts for anomalous spikes that may indicate ongoing exploitation attempts.
- Use intrusion detection/prevention systems (IDS/IPS) with rules to detect abnormally long header sequences in HTTP requests.
- Apply network rate limiting to throttle incoming connections and mitigate large-scale denial-of-service attempts.
Impact:
- Denial of Service: A single unauthenticated remote attacker can crash the WebSocket server process or render the host system unresponsive by exhausting all available memory.
- Service Disruption: Legitimate users experience connection failures, timeouts, or degraded performance as memory resources are consumed.
- Cascading Failures: If the vulnerable process runs on a shared host, memory exhaustion can affect co‑located services, leading to broader system instability.
- No Data Breach: The vulnerability does not expose or corrupt sensitive data; it is purely a resource exhaustion issue.
- Operational Cost: Recovery requires process restarts and may involve manual intervention, increasing operational overhead.
- Supply Chain Risk: Applications depending on websocket-driver inherit the vulnerability, making it a transitive risk for many Ruby, Node.js, and other ecosystems that bundle the library.
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Sources:
Reported By: nvd.nist.gov
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