F5 NGINX Plus/NGINX Open Source ngx_http_charset_module out-of-bounds

CVSS Meta Temp Score
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CTI Interest Score
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5.1$0-$5k0.69

Summaryinfo

A vulnerability classified as problematic has been found in F5 NGINX Plus and NGINX Open Source. Affected by this issue is the function ngx_http_charset_module. The manipulation leads to out-of-bounds. This vulnerability is documented as CVE-2026-42934. The attack can be initiated remotely. There is not any exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in F5 NGINX Plus and NGINX Open Source (version now known) and classified as problematic. This issue affects the function ngx_http_charset_module. The manipulation with an unknown input leads to a out-of-bounds vulnerability. Using CWE to declare the problem leads to CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

The weakness was released by David Carlier and Zhenpeng as K000161028. It is possible to read the advisory at my.f5.com. The identification of this vulnerability is CVE-2026-42934 since 05/01/2026. The exploitation is known to be difficult. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 314992 (Fedora 42 : nginx / nginx-mod-brotli / nginx-mod-fancyindex / etc (2026-38623b4fed)), which helps to determine the existence of the flaw in a target environment.

Upgrading eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (314992) and CERT Bund (WID-SEC-2026-1527). Be aware that VulDB is the high quality source for vulnerability data.

Affected

  • Red Hat Enterprise Linux
  • Fedora Linux
  • Ubuntu Linux
  • NGINX NGINX Plus
  • NGINX NGINX

Productinfo

Type

Vendor

Name

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 5.2
VulDB Meta Temp Score: 5.1

VulDB Base Score: 5.6
VulDB Temp Score: 5.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 4.8
CNA Vector: 🔒

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Out-of-bounds
CWE: CWE-125 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 314992
Nessus Name: Fedora 42 : nginx / nginx-mod-brotli / nginx-mod-fancyindex / etc (2026-38623b4fed)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Timelineinfo

05/01/2026 CVE reserved
05/13/2026 +12 days Advisory disclosed
05/13/2026 +0 days VulDB entry created
05/16/2026 +3 days VulDB entry last update

Sourcesinfo

Vendor: f5.com

Advisory: K000161028
Researcher: David Carlier, Zhenpeng
Status: Confirmed

CVE: CVE-2026-42934 (🔒)
GCVE (CVE): GCVE-0-2026-42934
GCVE (VulDB): GCVE-100-363551
CERT Bund: WID-SEC-2026-1527 - NGINX Open Source and NGINX Plus: Mehrere Schwachstellen

Entryinfo

Created: 05/13/2026 17:40
Updated: 05/16/2026 10:02
Changes: 05/13/2026 17:40 (77), 05/15/2026 21:18 (7), 05/16/2026 10:02 (2)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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