CVE-2026-42530

HIGH

NGINX Open-Source ngx_http_v3_module vulnerability

Title source: cna
STIX 2.1

Exploitation Summary

EIP tracks 4 public exploits for CVE-2026-42530. PoCs published by v4ltonn, HORKimhab, 0xBlackash.

AI-analyzed exploit summary The repository contains a scanner for CVE-2026-42530, which detects whether a remote nginx server is vulnerable to a QPACK encoder stream use-after-free vulnerability. It does not exploit the vulnerability but identifies it by observing the server's response to a crafted sequence of HTTP/3 streams.

Description

NGINX Open Source has a vulnerability in the ngx_http_v3_module module. When NGINX Open Source is configured to use the HTTP/3 QUIC module, a remote unauthenticated attacker along with conditions beyond their control can use a specially crafted HTTP/3 session to reopen a QPACK encoder stream. This may cause a Use-after-Free 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.

Exploits (4)

github SCANNER 1 stars
by v4ltonn · pythonpoc
https://github.com/v4ltonn/CVE-2026-42530

The repository contains a scanner for CVE-2026-42530, which detects whether a remote nginx server is vulnerable to a QPACK encoder stream use-after-free vulnerability. It does not exploit the vulnerability but identifies it by observing the server's response to a crafted sequence of HTTP/3 streams.

Classification
Scanner 100%
Attack Type
Other
Complexity
Moderate
Reliability
Reliable
Target: nginx 1.31.0, 1.31.1
No auth needed
Prerequisites: HTTP/3 support on the target server · aioquic library installed
mistral-large-3 · analyzed Jun 20, 2026 Full analysis →
github SUSPICIOUS
by HORKimhab · poc
https://github.com/HORKimhab/poc-cve-collection/tree/main/2026/42xxx/CVE-2026-42530.md

The repository contains no actual exploit code or technical analysis, only a high-level description of CVE-2026-42530 (a Use-after-Free in NGINX's HTTP/3 QUIC module). It links to external GitHub repos and an encrypted backup PoC, which are red flags for social engineering or malware distribution.

Classification
Suspicious 98%
Attack Type
Other
Complexity
Moderate
Reliability
Theoretical
Target: NGINX Open Source with ngx_http_v3_module (HTTP/3 QUIC enabled)
No auth needed
Prerequisites: NGINX configured with HTTP/3 QUIC module · ASLR disabled or bypassable (for code execution)
mistral-large-3 · analyzed Jul 10, 2026 Full analysis →
github SCANNER
by 0xBlackash · pythonpoc
https://github.com/0xBlackash/CVE-2026-42530

The repository contains a non-destructive scanner for CVE-2026-42530, a use-after-free vulnerability in NGINX HTTP/3 (QUIC). It checks for vulnerable versions by sending a safe HTTP/3 HEAD request and analyzing the Server header.

Classification
Scanner 95%
Attack Type
Dos
Complexity
Moderate
Reliability
Reliable
Target: NGINX 1.31.0, 1.31.1 with HTTP/3 enabled
No auth needed
Prerequisites: HTTP/3 (QUIC) enabled on target · Network access to port 443
mistral-large-3 · analyzed Jun 20, 2026 Full analysis →
github SUSPICIOUS
by HORKimhab · poc
https://github.com/HORKimhab/CVE-2026-42530

The repository lacks actual exploit code or technical details about CVE-2026-42530, instead providing generic setup instructions and a script to download external content. The README is filled with disclaimers and ethical use statements but no substantive vulnerability analysis.

Classification
Suspicious 90%
Attack Type
Other
Complexity
Theoretical
Reliability
Theoretical
Target: unspecified
No auth needed
Prerequisites: none specified
mistral-large-3 · analyzed Jun 19, 2026 Full analysis →

References (5)

Core 5

Scores

CVSS v3 8.1
EPSS 0.0368
EPSS Percentile 88.6%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact total

Details

CWE
CWE-416
Status published
Products (7)
F5/NGINX Open Source 1.31.0 - 1.31.2
f5/nginx_gateway_fabric 1.3.0 - 1.6.2
f5/nginx_ingress_controller 4.0.0
f5/nginx_ingress_controller 4.0.1
f5/nginx_ingress_controller 3.5.0 - 3.7.2
f5/nginx_instance_manager 2.17.0 - 2.22.0
f5/nginx_open_source 1.31.0 - 1.31.2
Published Jun 17, 2026
Tracked Since Jun 17, 2026