CVE-2023-6038
HIGHCVE-2023-6038 is a high-severity (CVSS 7.5) CWE-862 vulnerability in h2o h2o. 1 public exploit reference exists, so weaponization risk is real. O3 Security detects and blocks CVE-2023-6038 exploitation at runtime via eBPF exploit-chain detection and L7 egress monitoring, even on unpatched systems.
A Local File Inclusion (LFI) vulnerability exists in the h2o-3 REST API, allowing unauthenticated remote attackers to read arbitrary files on the server with the permissions of the…
Description
A Local File Inclusion (LFI) vulnerability exists in the h2o-3 REST API, allowing unauthenticated remote attackers to read arbitrary files on the server with the permissions of the user running the h2o-3 instance. This issue affects the default installation and does not require user interaction. The vulnerability can be exploited by making specific GET or POST requests to the ImportFiles and ParseSetup endpoints, respectively. This issue was identified in version 3.40.0.4 of h2o-3.
Affected Products
h2oh2oResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Vendor / applianceDetect
Inventory every h2o h2o deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for exploitation at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.
Remediation status
No patch has shipped for CVE-2023-6038 yet — track the h2o h2o advisory for a fixed release and apply the workarounds below in the meantime.
Mitigate without a patch
Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.
How O3 protects you
O3 detects and blocks CVE-2023-6038 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.
Tailored to CVE-2023-6038. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-6038 being exploited in your environment?
O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2023-6038 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.