NGINX Plus
CVE-2026-48142
MEDIUM
Severity by source
CVSS:4.0/AV:N/AC:H/AT:N/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
AV:N for network-delivered HTTP requests; AC:H for dual stacked prerequisites (non-default config plus content-dependent conditions); C:L and A:L for partial heap leak and worker restart only.
AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L
Primary rating from Vendor (f5).
CVSS VectorVendor: f5
Lifecycle Timeline
2DescriptionCVE.org
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_charset_module module. When content is served or proxied through a location block with both source_charset utf-8; and a charset directive (for example, charset koi8-r;) configured, remote, unauthenticated attackers can send requests (in conjunction with conditions beyond their 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.
AnalysisAI
Heap buffer over-read in NGINX Plus and NGINX Open Source's ngx_http_charset_module exposes limited worker process memory or triggers a worker restart when remote unauthenticated attackers send crafted requests against a non-default charset conversion configuration. Exploitation requires both a specific dual-directive configuration (source_charset utf-8 alongside a differing charset directive such as koi8-r in the same location block) and content-dependent conditions outside the attacker's direct control, reflected in the CVSS AC:H rating. No public exploit code exists and this CVE does not appear in the CISA KEV catalog; the vendor F5 has published advisory K000161585 with patched version guidance.
Technical ContextAI
The ngx_http_charset_module is a built-in NGINX module that performs on-the-fly character encoding conversion between declared source and target charsets for proxied or served response bodies. When a location block simultaneously declares source_charset utf-8 and a charset directive targeting a different encoding (e.g., koi8-r), the module walks multibyte UTF-8 sequences during conversion. CWE-125 (Out-of-bounds Read) identifies the root cause: the conversion logic reads beyond the boundary of its heap-allocated buffer, likely due to insufficient length validation when iterating over variable-width UTF-8 code points. CPE data confirms both F5's commercial offering (cpe:2.3:a:f5:nginx_plus) and the community distribution (cpe:2.3:a:f5:nginx_open_source) are affected, with wildcard version ranges indicating all supported releases are in scope. The vulnerability is isolated to the worker process, limiting blast radius to memory leakage or a graceful worker restart rather than full process compromise.
RemediationAI
Consult F5 advisory K000161585 at https://my.f5.com/manage/s/article/K000161585 for exact patched NGINX Plus and NGINX Open Source version numbers, which were not independently confirmed from the available intelligence. As an immediate compensating control, audit all NGINX location blocks and remove any co-occurrence of source_charset and a differing charset directive in the same block; eliminating this dual-directive combination entirely removes the vulnerable code path, though at the cost of disabling charset conversion for affected endpoints - a trade-off only acceptable if charset transcoding is non-functional for those routes. If charset conversion is a required feature and patching is delayed, restrict access to affected location blocks using NGINX's allow/deny directives or upstream network ACLs to reduce the attacker pool, accepting reduced availability in exchange for risk reduction. Do not rely on rate limiting alone as a mitigation, since a single well-timed request with suitable response content is sufficient to trigger the over-read.
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View allSame technique Buffer Overflow
View allVendor StatusVendor
SUSE
Severity: Moderate| Product | Status |
|---|---|
| openSUSE Tumbleweed | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP7 | Affected |
| SUSE Linux Enterprise Module for Server Applications 15 SP7 | Affected |
| SUSE Linux Enterprise Server 15 SP7 | Affected |
| SUSE Linux Enterprise Server 16.0 | Affected |
| SUSE Linux Enterprise Server 16.1 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP7 | Affected |
| SUSE Linux Enterprise Server for SAP applications 16.0 | Affected |
| SUSE Linux Enterprise Server for SAP applications 16.1 | Affected |
| openSUSE Leap 16.0 | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4 | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5 | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | Affected |
| SUSE Linux Enterprise Module for Server Applications 15 SP4 | Affected |
| SUSE Linux Enterprise Module for Server Applications 15 SP5 | Affected |
| SUSE Linux Enterprise Module for Server Applications 15 SP6 | Affected |
| SUSE Linux Enterprise Server 15 SP4 | Affected |
| SUSE Linux Enterprise Server 15 SP4-LTSS | Affected |
| SUSE Linux Enterprise Server 15 SP5 | Affected |
| SUSE Linux Enterprise Server 15 SP5-LTSS | Affected |
| SUSE Linux Enterprise Server 15 SP6 | Affected |
| SUSE Linux Enterprise Server 15 SP6-LTSS | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | Affected |
| SUSE Manager Proxy 4.3 | Affected |
| SUSE Manager Proxy LTS 4.3 | Affected |
| SUSE Manager Retail Branch Server 4.3 | Affected |
| SUSE Manager Retail Branch Server LTS 4.3 | Affected |
| SUSE Manager Server 4.3 | Affected |
| SUSE Manager Server LTS 4.3 | Affected |
| SUSE CaaS Platform 4.0 | Affected |
| SUSE Enterprise Storage 6 | Affected |
| SUSE Enterprise Storage 7 | Affected |
| SUSE Enterprise Storage 7.1 | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1 | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1-ESPOS | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1-LTSS | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2 | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2-ESPOS | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2-LTSS | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3 | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3-ESPOS | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3-LTSS | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP6 | Affected |
| SUSE Linux Enterprise Module for Server Applications 15 SP1 | Affected |
| SUSE Linux Enterprise Module for Server Applications 15 SP2 | Affected |
| SUSE Linux Enterprise Module for Server Applications 15 SP3 | Affected |
| SUSE Linux Enterprise Real Time 15 SP2 | Affected |
| SUSE Linux Enterprise Real Time 15 SP3 | Affected |
| SUSE Linux Enterprise Real Time 15 SP4 | Affected |
| SUSE Linux Enterprise Server 15 SP1 | Affected |
| SUSE Linux Enterprise Server 15 SP1-BCL | Affected |
| SUSE Linux Enterprise Server 15 SP1-LTSS | Affected |
| SUSE Linux Enterprise Server 15 SP2 | Affected |
| SUSE Linux Enterprise Server 15 SP2-BCL | Affected |
| SUSE Linux Enterprise Server 15 SP2-LTSS | Affected |
| SUSE Linux Enterprise Server 15 SP3 | Affected |
| SUSE Linux Enterprise Server 15 SP3-BCL | Affected |
| SUSE Linux Enterprise Server 15 SP3-LTSS | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP1 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP2 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP3 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP4 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | Affected |
| SUSE Manager Proxy 4.0 | Affected |
| SUSE Manager Proxy 4.1 | Affected |
| SUSE Manager Proxy 4.2 | Affected |
| SUSE Manager Retail Branch Server 4.0 | Affected |
| SUSE Manager Retail Branch Server 4.1 | Affected |
| SUSE Manager Retail Branch Server 4.2 | Affected |
| SUSE Manager Server 4.0 | Affected |
| SUSE Manager Server 4.1 | Affected |
| SUSE Manager Server 4.2 | Affected |
| openSUSE Leap 15.3 | Affected |
| openSUSE Leap 15.4 | Affected |
| openSUSE Leap 15.5 | Affected |
| openSUSE Leap 15.6 | Affected |
| private-registry/1.2/harbor-portal private-registry/harbor-nginx private-registry/harbor-portal suse/nginx suse/rmt-nginx | Affected |
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