NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module. This vulnerability exists when a rewrite directive uses a regex pattern with distinct, overlapping Perl-Compatible Regular Expression (PCRE) captures (for example, ^/((.*))$) and a replacement string that references multiple such captures (for example, $1$2) in a redirect or arguments context. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.
Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Metrics
Affected Vendors & Products
References
| Link | Providers |
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| https://my.f5.com/manage/s/article/K000161377 |
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History
Fri, 22 May 2026 15:45:00 +0000
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| First Time appeared |
F5
F5 nginx Open Source F5 nginx Plus |
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| Vendors & Products |
F5
F5 nginx Open Source F5 nginx Plus |
Fri, 22 May 2026 15:30:00 +0000
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| Metrics |
ssvc
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Fri, 22 May 2026 14:30:00 +0000
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| Description | NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module. This vulnerability exists when a rewrite directive uses a regex pattern with distinct, overlapping Perl-Compatible Regular Expression (PCRE) captures (for example, ^/((.*))$) and a replacement string that references multiple such captures (for example, $1$2) in a redirect or arguments context. 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. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated. | |
| Title | NGINX ngx_http_rewrite_module vulnerability | |
| Weaknesses | CWE-122 | |
| References |
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| Metrics |
cvssV3_1
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Status: PUBLISHED
Assigner: f5
Published:
Updated: 2026-05-23T03:55:52.757Z
Reserved: 2026-05-21T20:58:58.484Z
Link: CVE-2026-9256
Updated: 2026-05-23T00:35:26.077Z
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OpenCVE Enrichment
Updated: 2026-05-22T15:45:16Z