Bug 2501307

Summary: CVE-2026-42533 nginx: NGINX: Arbitrary code execution via crafted HTTP requests [fedora-all]
Product: [Fedora] Fedora Reporter: Michalis Papadopoullos <mpapadop>
Component: nginxAssignee: Felix Kaechele <felix>
Status: CLOSED ERRATA QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: medium Docs Contact:
Priority: unspecified    
Version: rawhideCC: felix, gizzi, gsciorti, jorton, luhliari, mikel, pavel.lisy
Target Milestone: ---Keywords: Security, SecurityTracking
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["12821b3f-83fb-4ae2-aedd-7becd1675278"]}
Fixed In Version: nginx-1.30.4-1.fc44 Doc Type: ---
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2026-07-23 01:19:30 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description Michalis Papadopoullos 2026-07-16 12:55:04 UTC
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and a string expression 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.

Comment 1 Fedora Update System 2026-07-20 20:48:37 UTC
FEDORA-2026-60fc198d3b (nginx-1.30.4-1.fc44, nginx-mod-brotli-1.0.0~rc-13.fc44, and 6 more) has been submitted as an update to Fedora 44.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-60fc198d3b

Comment 2 Fedora Update System 2026-07-23 01:19:30 UTC
FEDORA-2026-60fc198d3b (nginx-1.30.4-1.fc44, nginx-mod-brotli-1.0.0~rc-13.fc44, and 6 more) has been pushed to the Fedora 44 stable repository.
If problem still persists, please make note of it in this bug report.