Vulnerabilities
Misconfiguration
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CVE Vulnerabilities

CVE-2026-42055

Heap-based Buffer Overflow

Published: Jun 17, 2026 | Modified: Jul 09, 2026
CVSS 3.x
N/A
Source:
NVD
CVSS 2.x
RedHat/V2
RedHat/V3
8.1 IMPORTANT
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Ubuntu
MEDIUM
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Additional information
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2026-42055
CWEhttps://cwe.mitre.org/data/definitions/122.html

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_proxy_v2_module and ngx_http_grpc_module modules. This vulnerability exists when the proxy_http_version to 2 or grpc_pass directives are used to proxy HTTP/2 traffic, the ignore_invalid_headers directive is set to off, and the large_client_header_buffers directive size is larger than 2 megabytes. A remote, unauthenticated attacker, along with conditions beyond their control, could send large headers while creating an upstream request. This may cause a heap-based 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.

Weakness

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

Affected Software

NameVendorStart VersionEnd Version
DosF54.9.0 (including)4.9.0 (including)
Nginx_app_protect_dosF54.3.0 (including)4.7.0 (including)
Nginx_app_protect_wafF54.10.0 (including)4.16.0 (including)
Nginx_app_protect_wafF55.2.0 (including)5.8.0 (including)
Nginx_gateway_fabricF51.3.0 (including)1.6.2 (including)
Nginx_gateway_fabricF52.0.0 (including)2.6.4 (excluding)
Nginx_ingress_controllerF53.5.0 (including)3.7.2 (including)
Nginx_ingress_controllerF55.0.0 (including)5.5.1 (excluding)
Nginx_ingress_controllerF54.0.0 (including)4.0.0 (including)
Nginx_ingress_controllerF54.0.1 (including)4.0.1 (including)
Nginx_instance_managerF52.17.0 (including)2.22.0 (including)
Nginx_open_sourceF51.30.0 (including)1.30.3 (excluding)
Nginx_open_sourceF51.31.1 (including)1.31.1 (including)
Nginx_plusF537.0.0 (including)37.0.1 (including)
Nginx_plusF5r3 (including)r3 (including)
Nginx_plusF5r30 (including)r30 (including)
Nginx_plusF5r30-p1 (including)r30-p1 (including)
Nginx_plusF5r30-p2 (including)r30-p2 (including)
Nginx_plusF5r31 (including)r31 (including)
Nginx_plusF5r31-p1 (including)r31-p1 (including)
Nginx_plusF5r31-p2 (including)r31-p2 (including)
Nginx_plusF5r31-p3 (including)r31-p3 (including)
Nginx_plusF5r32 (including)r32 (including)
Nginx_plusF5r32-p1 (including)r32-p1 (including)
Nginx_plusF5r32-p2 (including)r32-p2 (including)
Nginx_plusF5r32-p3 (including)r32-p3 (including)
Nginx_plusF5r32-p4 (including)r32-p4 (including)
Nginx_plusF5r33 (including)r33 (including)
Nginx_plusF5r33-p1 (including)r33-p1 (including)
Nginx_plusF5r33-p2 (including)r33-p2 (including)
Nginx_plusF5r33-p3 (including)r33-p3 (including)
Nginx_plusF5r34 (including)r34 (including)
Nginx_plusF5r34-p1 (including)r34-p1 (including)
Nginx_plusF5r34-p2 (including)r34-p2 (including)
Nginx_plusF5r35 (including)r35 (including)
Nginx_plusF5r35-p1 (including)r35-p1 (including)
Nginx_plusF5r36 (including)r36 (including)
Nginx_plusF5r36-p1 (including)r36-p1 (including)
Nginx_plusF5r36-p2 (including)r36-p2 (including)
Nginx_plusF5r36-p3 (including)r36-p3 (including)
Nginx_plusF5r36-p4 (including)r36-p4 (including)
Nginx_plusF5r36-p5 (including)r36-p5 (including)
WafF55.9.0 (including)5.13.1 (including)
WafF54.8.1 (including)4.8.1 (including)
Red Hat Enterprise Linux 10RedHatnginx-2:1.26.3-6.el10_2.5*
Red Hat Enterprise Linux 9RedHatnginx-2:1.20.1-28.el9_8.4*
Red Hat Enterprise Linux 9RedHatnginx:1.24-9080020260707164406.9*
Red Hat Enterprise Linux 9RedHatnginx:1.26-9080020260707110000.9*
Red Hat Hardened ImagesRedHatnginx-main-1.30.3-2.hum1*
NginxUbuntudevel*
NginxUbuntujammy*
NginxUbuntunoble*
NginxUbuntuquesting*
NginxUbunturesolute*
NginxUbuntuupstream*

Potential Mitigations

  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking.
  • D3-SFCV (Stack Frame Canary Validation) from D3FEND [REF-1334] discusses canary-based detection in detail.
  • Run or compile the software using features or extensions that randomly arrange the positions of a program’s executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code.
  • Examples include Address Space Layout Randomization (ASLR) [REF-58] [REF-60] and Position-Independent Executables (PIE) [REF-64]. Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as “rebasing” (for Windows) and “prelinking” (for Linux) [REF-1332] using randomly generated addresses. ASLR for libraries cannot be used in conjunction with prelink since it would require relocating the libraries at run-time, defeating the whole purpose of prelinking.
  • For more information on these techniques see D3-SAOR (Segment Address Offset Randomization) from D3FEND [REF-1335].

References

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