CVE-2026-42934

Published May 13, 2026

Last updated 6 days ago

CVSS medium 6.3

Overview

Description
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_charset_module module. When charset, source_charset, and charset_map and proxy_pass with disabled buffering ("off") directives are configured, unauthenticated attackers can send requests that with conditions beyond the attackers' control to cause a heap buffer over-read in the NGINX worker process, leading to limited disclosure of memory or a restart.  Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Source
f5sirt@f5.com
NVD status
Analyzed
Products
dos, nginx_gateway_fabric, nginx_ingress_controller, nginx_instance_manager, nginx_open_source, nginx_plus, waf

Risk scores

CVSS 4.0

Type
Secondary
Base score
6.3
Impact score
-
Exploitability score
-
Vector string
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Severity
MEDIUM

CVSS 3.1

Type
Secondary
Base score
4.8
Impact score
2.5
Exploitability score
2.2
Vector string
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L
Severity
MEDIUM

Weaknesses

f5sirt@f5.com
CWE-125

Social media

Hype score
Not currently trending

  1. More chained vulns are being discovered because of AI tools NGINX Rift is the latest Remote Code Execution (RCE), that combines 4 vulns CVE-2026-42945 Critical (9.2) CVE-2026-42946 High (8.3) CVE-2026-40701 Medium (6.3) CVE-2026-42934 Medium (6.3) https://t.co/uEtbOYgtwJ

    @Matt_Rosenquist

    15 May 2026

    91 Impressions

    0 Retweets

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  2. Nginx 1.31.0 Security Update - 6 CVEs Fixed CVE-2026-42945 - Heap buffer overflow in ngx_http_rewrite_module (potential code execution) CVE-2026-42926 - HTTP/2 request injection via proxy_set_body CVE-2026-42946 CVE-2026-42934 CVE-2026-40460 CVE-2026-40701 https://t.co/eRNItKkZ

    @vutruso

    15 May 2026

    63 Impressions

    0 Retweets

    0 Likes

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    0 Quotes

Configurations

Related CVEs

  1. When NGINX Plus or NGINX Open Source is configured as the data plane for NGINX Gateway Fabric, an injection vulnerability exists in the NGINX configuration generator component of NGINX Gateway Fabric. User-supplied string values from the NginxProxy Custom Resource Definition (CRD) access log format setting are rendered directly into NGINX configuration templates without sanitization or escaping. An authenticated attacker with permission to create or modify these CRDs may craft values that inject arbitrary NGINX configuration directives. This is a control plane issue; there is no data plane exposure from the vulnerability trigger itself. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.•CVE-2026-50107
  2. NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_charset_module module. When content is served or proxied through a location block with both source_charset utf-8; and a charset directive (for example, charset koi8-r;) configured, remote, unauthenticated attackers can send requests (in conjunction with conditions beyond their control) to cause a heap buffer over-read in the NGINX worker process, leading to limited disclosure of memory or a restart. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.•CVE-2026-48142
  3. 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.•CVE-2026-9256
  4. A vulnerability exists in the ngx_http_scgi_module and ngx_http_uwsgi_module modules that may result in excessive memory allocation or an over-read of data. When scgi_pass or uwsgi_pass is configured, an unauthenticated attacker with man-in-the-middle (MITM) ability to control responses from an upstream server may be able to read the memory of the NGINX worker process or restart it.  Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.•CVE-2026-42946
  5. NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module. This vulnerability exists when the rewrite directive is followed by a rewrite, if, or set directive and an unnamed Perl-Compatible Regular Expression (PCRE) capture (for example, $1, $2) with a replacement string that includes a question mark (?). An unauthenticated attacker along with conditions beyond its 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.•CVE-2026-42945

References

Sources include official advisories and independent security research.