Skip to content
Fencer Vulns
medium 4.8

CVE-2026-42934 json

NGINX ngx_http_charset_module vulnerability

published 2026-05-13 5 mo ago modified 2026-10-26 13 d ago also BIT-nginx-2026-42934 , BIT-nginx-gateway-2026-42934 , EUVD-2026-30008

cvss
4.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 54%
public exploits
0
none known

Summary

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_charset_module module. When charset, source_charset, and charset_map and proxy_pass with disabled buffering ("off") directives are configured, unauthenticated attackers can send requests that with conditions beyond the attackers' control to cause a heap buffer over-read in the NGINX worker process, leading to limited disclosure of memory or a restart.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Patch / fix

  • bitnami nginx 1.30.1
  • bitnami nginx-gateway 1.30.1
  • F5 NGINX Plus R32 P6, R36 P4, R37
  • F5 NGINX Open Source 1.30.1, 1.31.0
  • nginx Debian 12 1.22.1-9+deb12u7
  • nginx Debian 13 1.26.3-3+deb13u5
  • nginx Debian 14 1.30.0-4

debian advisories DEBIAN-CVE-2026-42934

  • nginx Ubuntu 22.04 LTS 1.18.0-6ubuntu14.12
  • nginx Ubuntu 24.04 LTS 1.24.0-2ubuntu7.9
  • nginx Ubuntu 25.10 1.28.0-6ubuntu1.4
  • nginx Ubuntu 26.04 LTS 1.28.3-2ubuntu1.2
  • nginx Ubuntu Pro 14.04 LTS 1.4.6-1ubuntu3.9+esm6
  • nginx Ubuntu Pro 16.04 LTS 1.10.3-0ubuntu0.16.04.5+esm7
  • nginx Ubuntu Pro 18.04 LTS 1.14.0-0ubuntu1.11+esm2
  • nginx Ubuntu Pro 20.04 LTS 1.18.0-0ubuntu1.7+esm1

ubuntu advisories UBUNTU-CVE-2026-42934

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • nginx SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +5 more 1.21.5-150400.3.20.1

suse advisories SUSE-SU-2026:2370-1

  • nginx openSUSE Tumbleweed 1.31.0-1.1

opensuse advisories openSUSE-SU-2026:10796-1

  • nginx Alpine 3.21 1.26.3-r1
  • nginx Alpine 3.23, Alpine 3.22 1.28.3-r1
  • nginx Alpine 3.24 1.30.1-r0

alpine advisories ALPINE-CVE-2026-42934

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • nginx Azure Linux 3.0 1.28.3-4

azure linux advisories AZL-86853

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-42934 updated cvss 4.8

nginx: ngx_http_charset_module: information disclosure and denial of service

  • Red Hat Enterprise Linux 8 nginx, nginx-mod-mail, nginx-filesystem, nginx-mod-stream, nginx-all-modules, nginx-mod-http-perl, +2 more Red Hat Enterprise Linux 9 nginx, nginx-core, nginx-mod-mail, nginx-filesystem, nginx-mod-stream, nginx-all-modules, +3 more
    affected: workaround, no fix available “To mitigate this vulnerability, enable proxy buffering (the default configuration).”
  • Red Hat Enterprise Linux 10 nginx
    affected: workaround, no fix planned “To mitigate this vulnerability, enable proxy buffering (the default configuration).”
  • Red Hat Lightspeed proxy 1 insights-proxy/insights-proxy-container-rhel9
    affected: workaround, no fix available “To mitigate this vulnerability, enable proxy buffering (the default configuration).”
  • Red Hat Hardened Images nginx
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

0.73% chance of exploitation in the next 30 days, higher than 54% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 4.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L
CNA 4.0 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N
CNA 4.0 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected packages

ecosystem package affected fixed in
bitnami nginx
>=0.3.50, <1.30.1
1.30.1
bitnami nginx-gateway
>=0.3.50, <1.30.1
1.30.1

Affected products

  • F5 NGINX Plus
  • F5 NGINX Open Source

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.