CVE-2026-42055

Publication date 19 June 2026

Last updated 25 June 2026

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

8.1 · High

Score breakdown

Description

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.

Status

Package Ubuntu Release Status
nginx 26.04 LTS resolute
Fixed 1.28.3-2ubuntu1.6
25.10 questing
Fixed 1.28.0-6ubuntu1.8
24.04 LTS noble
Fixed 1.24.0-2ubuntu7.13
22.04 LTS jammy
Fixed 1.18.0-6ubuntu14.16
20.04 LTS focal
Needs evaluation
18.04 LTS bionic
Needs evaluation
16.04 LTS xenial
Needs evaluation
14.04 LTS trusty
Needs evaluation

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package Patch details
nginx

Severity score breakdown

CVSS version:

Base score 9.2 · Critical

Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Base score 8.1 · High

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

References

Related Ubuntu Security Notices (USN)

Other references

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