SB2026060701 - Debian update for nginx
Published: June 7, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 2 vulnerabilities.
1) Heap-based buffer overflow (CVE-ID: CVE-2026-9256)
CWE-ID: CWE-122 - Heap-based Buffer Overflow
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Red
The vulnerability allows a remote attacker to compromise the affected system.
The vulnerability exists due to heap-based buffer overflow in ngx_http_rewrite_module when processing crafted HTTP requests that trigger rewrite directives using overlapping PCRE captures and multiple capture references in a redirect or arguments context. A remote attacker can send crafted HTTP requests to execute arbitrary code or crash the web server.
There is no control plane exposure; this is a data plane issue only. Code execution is possible on systems with ASLR disabled or when ASLR can be bypassed.
2) Uncontrolled Memory Allocation (CVE-ID: CVE-2026-42946)
CWE-ID: CWE-789 - Uncontrolled Memory Allocation
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Green
The vulnerability allows a remote attacker to disclose memory contents of the NGINX worker process or cause a denial of service.
The vulnerability exists due to memory allocation with excessive size value and use of out-of-range pointer offset in the ngx_http_scgi_module and ngx_http_uwsgi_module modules when processing responses from an upstream server via scgi_pass or uwsgi_pass. A remote attacker can control responses from an upstream server to disclose memory contents of the NGINX worker process or cause a denial of service.
Exploitation requires man-in-the-middle ability to control responses from an upstream server. There is no control plane exposure; this is a data plane issue only.
Remediation
Install update from vendor's website.