CVE-2024-4436 – This vulnerability is an incomplete fix for CVE... (How to Fix)

Q: What is the severity of CVE-2024-4436?

CVE-2024-4436 has a CVSS score of 7.5 (HIGH). This vulnerability is an incomplete fix for CVE-2022-41723 in the etcd package distributed with Red Hat OpenStack platform. It allows potential HTTP/2 rapid reset attacks leading to denial of service. Only Red Hat OpenStack platform deployments using the affected etcd package are impacted.

📋 TL;DR

This vulnerability is an incomplete fix for CVE-2022-41723 in the etcd package distributed with Red Hat OpenStack platform. It allows potential HTTP/2 rapid reset attacks leading to denial of service. Only Red Hat OpenStack platform deployments using the affected etcd package are impacted.

💻 Affected Systems

Products:

Red Hat OpenStack Platform

Versions: Specific versions mentioned in RHSA-2024:3352 and RHSA-2024:3467 advisories

Operating Systems: Red Hat Enterprise Linux

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects etcd packages distributed with Red Hat OpenStack platform that use http://golang.org/x/net/http2 instead of the RHEL-provided version.

⚠️ Manual Verification Required

This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.

Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).

🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.

Recommended Actions:

Review the CVE details at NVD
Check vendor security advisories for your specific version
Test if the vulnerability is exploitable in your environment
Consider updating to the latest version as a precaution

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete denial of service for etcd services, potentially disrupting OpenStack control plane operations and causing cascading failures in cloud infrastructure.

🟠

Likely Case

Degraded performance or intermittent service disruptions in etcd clusters, affecting OpenStack API availability and component communication.

🟢

If Mitigated

Minimal impact with proper network segmentation and rate limiting in place, though service degradation may still occur under heavy attack.

🌐 Internet-Facing: MEDIUM - etcd services should not be internet-facing in proper OpenStack deployments, but misconfigurations could expose them.

🏢 Internal Only: HIGH - etcd is critical internal infrastructure for OpenStack, and successful attacks could disrupt entire cloud operations.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Based on CVE-2022-41723 exploitation patterns, HTTP/2 rapid reset attacks are well-documented and relatively easy to execute.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Versions specified in RHSA-2024:3352 and RHSA-2024:3467

Vendor Advisory: https://access.redhat.com/errata/RHSA-2024:3352

Restart Required: Yes

Instructions:

1. Apply Red Hat OpenStack Platform updates via 'yum update' 2. Restart etcd services 3. Verify service functionality

🔧 Temporary Workarounds

Network segmentation and firewall rules

linux

Restrict access to etcd services to only necessary OpenStack components

iptables -A INPUT -p tcp --dport 2379 -s <trusted_subnet> -j ACCEPT
iptables -A INPUT -p tcp --dport 2379 -j DROP

HTTP/2 connection limiting

linux

Configure reverse proxy or load balancer to limit concurrent HTTP/2 connections

# Configure in nginx: http2_max_concurrent_streams 100;
# Configure in haproxy: tune.h2.initial-window-size 65535

🧯 If You Can't Patch

Implement strict network access controls to limit etcd exposure
Deploy rate limiting and DDoS protection for etcd endpoints

🔍 How to Verify

Check if Vulnerable:

Check etcd package version: rpm -q etcd and compare against patched versions in RHSA advisories

Check Version:

rpm -q etcd --queryformat '%{VERSION}-%{RELEASE}\n'

Verify Fix Applied:

Verify updated package version and test etcd cluster health with 'etcdctl endpoint health'

📡 Detection & Monitoring

Log Indicators:

Unusual HTTP/2 connection resets in etcd logs
High rate of connection attempts to port 2379/2380
etcd cluster health degradation warnings

Network Indicators:

Spike in RST_STREAM frames to etcd ports
Abnormal HTTP/2 traffic patterns to etcd services

SIEM Query:

source="etcd.log" AND ("RST_STREAM" OR "connection reset" OR "too many streams")

📊 Metadata

CVE ID: CVE-2024-4436

CVSS v3 Score: 7.5 (HIGH)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE: CWE-400

Published: May 8, 2024

Last Updated: November 21, 2024

🔗 References

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