Heap-based Buffer Overflow Affecting nginx package, versions [1.0.0,1.30.2)[1.31.0,1.31.1)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published24 May 2026
- disclosed22 May 2026
- creditMufeed VH, Nebula Security, Vexera AI
Introduced: 22 May 2026
CVE-2026-9256 (opens in a new tab)How to fix?
Upgrade nginx to version 1.30.2, 1.31.1 or higher.
Overview
Affected versions of this package are vulnerable to Heap-based Buffer Overflow in the ngx_http_rewrite_module when a rewrite directive uses a regex pattern with distinct, overlapping Perl-Compatible Regular Expression (PCRE) captures and a replacement string that references multiple such captures in a redirect or arguments context. An attacker can cause a heap buffer overflow in the worker process, potentially leading to process restart or remote code execution by sending crafted HTTP requests. This is only exploitable if Address Space Layout Randomization (ASLR) is disabled or the attacker can bypass ASLR.