OESA-2026-4543: nginx security update
NGINX is a free, open-source, high-performance HTTP server and reverse proxy, as well as an IMAP/POP3 proxy server. Security Fix(es):
A vulnerability exists in NGINX Plus and NGINX Open Source when a location is configured that uses the alias directive together with rewrite and a set or return directive referencing the $requestfilename variable. Alternatively, the same result could be achieved when the $requestfilename variable is used in an access log format directive. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.
Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. There is no control plane exposure; this is a data plane issue only.
Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-15176)
A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and the root directive or access log format references the map's regex capture variables before referencing the map output variable. Alternatively, the same result could be achieved by using a non-cacheable variable in a string expression under certain conditions. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.
Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. There is no control plane exposure; this is a data plane issue only.
Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-93479)
NGINX Plus and NGINX Open Source have a vulnerability in the ngxhttpcoremodule module. When asynchronous file I/O (AIO) is enabled in certain configurations, processing a Server Side Includes (SSI) page containing “include virtual” commands may trigger a Use-After-Free (UAF) in the NGINX worker process. This may cause memory corruption or a worker process crash. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.
Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system, corrupt its memory, or possibly trigger code execution. There is no control plane exposure; this is a data plane issue only.
Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.(CVE-2026-97205)
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
openeuler/nginxto a version that resolves this vulnerability.Fixed in 1.21.5-20.oe2203sp4
Event History
Child vulnerabilities
Contains the following vulnerabilities.
Frequently Asked Questions
Which deployments are exposed to the heap buffer overflow condition?
NGINX Plus and NGINX Open Source deployments are affected when a location uses alias with rewrite and a set or return directive that references $request_filename. The condition can also occur when $request_filename is used in an access-log format directive.
Does an attacker need credentials or control-plane access?
No authentication is required. The issue is in the data plane and has no control-plane exposure; exploitation involves crafted HTTP requests and additional conditions beyond the attacker's control.
What is the likely impact of a successful attack?
The overflow can cause an NGINX worker process to restart, resulting in denial of service. Code execution may be possible where ASLR is disabled or where an attacker can bypass ASLR.
Are unsupported software releases covered by the evaluation?
No. Software versions that have reached End of Technical Support are not evaluated.