CVE-2026-42530

HIGH 8.1

NGINX Open-Source ngx_http_v3_module vulnerability

CVSS Score

8.1

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-416
Vendor	f5
Product	nginx open source
Published	Jun 17, 2026
Last Updated	Jun 17, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Affected Versions

F5 / NGINX Open Source

1.31.0 < 1.31.2

References

NVD ↗ CVE.org ↗ EPSS Data ↗

my.f5.com: https://my.f5.com/manage/s/article/K000161616

Credits

🔍 "F5 acknowledges Trung Nguyen (@everping) of CyStack, Zhenpeng (Leo) Lin (depthfirst), Evan Hellman (@xintenseapple) of Trail of Bits in collaboration with OpenAI, AntAISecurityLab, and Nebula Security (@nebusecurity) for bringing this issue to our attention and following the highest standards of coordinated disclosure."