🛡️ CVE-2026-42055 on Ubuntu — nginx

⚪ Unknown ✅ No Known Exploit OSV
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

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.

Distribution advisory

This page covers CVE-2026-42055 as tracked by Ubuntu, for the package nginx. The fix is available in version 1.28.3-2ubuntu1.6; earlier versions remain affected.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. Rated impact: confidentiality high, integrity high, availability high.

Affected software

UBUNTU-CVE-2026-42055 is recorded against 1 package.

  • nginx (fixed in 1.28.3-2ubuntu1.6)

Timeline and source

Published on 19 June 2026 and last revised on 2 July 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

ubuntu.com (Report)
www.cve.org (Report)
my.f5.com (Report)
ubuntu.com (Advisory)

Details

Severity Unknown
CVSS Score N/A
CVSS 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
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2026-06-19
Updated 2026-08-12
Modified 2026-07-02
Fix URL N/A

Affected Packages

Software From version Fixed in
nginx — 1.28.3-2ubuntu1.6

Exploit Protection

Are you running nginx?

UBUNTU-CVE-2026-42055 carries CVSS 9.5 Critical rating. BotEraser checks your installation against this and other known CVE records, and blocks IPs associated with exploit activity.

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