MediumCVE-2026-48142

    NGINX ngx_http_charset_module vulnerability (CVE-2026-48142)

    Published Last modified Sources: Debian LTS, Debian, Red Hat, Ubuntu, BSI, Msrc Update Guide, F5, OSV, CVE.org

    What is affected, what to do

    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.

    Update F5 NGINX Open Source to version 1.31.2, F5 NGINX Open Source to version 1.30.3, F5 NGINX Plus to version 37.0.2.1.

    Affected
    • F5 NGINX Open Source lt 1.13.10..1.31.2
    • F5 NGINX Open Source lt 1.30.0..1.30.3
    • F5 NGINX Plus lt 37.0..37.0.2.1
    • F5 NGINX Plus gte R36..*
    Fixed in
    • F5 NGINX Open Source 1.31.2
    • F5 NGINX Open Source 1.30.3
    • F5 NGINX Plus 37.0.2.1

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    6.3

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: NVD, CVSS v4

    4.8

    CVSS v3

    Severity Medium on the scale from 0 to 10.

    Source: Debian LTS, Debian, Red Hat, Ubuntu, BSI, Msrc Update Guide, F5, OSV, CVE.org

    0.7 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 52.4

    Show all metrics
    Severity
    Medium
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    72.58 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    no public PoC known
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    6.3 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    4.8
    CVSS v4

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    6.3
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    0.7 %
    Low — model estimates < 1% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    52.4
    High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    —
    Published
    CISA assessment (SSVC)
    Exploitation: none known · not automatable · Technical impact: partial
    Source: CISA Vulnrichment, as of 17 June 2026
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-125

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    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.

    Source: Debian LTS Advisories, Debian Security Advisories, redhat_csaf, Ubuntu Security Notices, BSI WID Portal, BSI CSAF, Microsoft Security Update Guide, f5_askf5, OSV (Open Source Vulnerabilities), NVD (NIST), cvelistv5

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    F5NGINX Open Source
    • 1.30.0 – < 1.30.3
    • 1.13.10 – < 1.31.2
    • 1.30.3
    • 1.31.2
    F5NGINX Plus
    • ≥ R36
    • 37.0 – < 37.0.2.1
    • —
    • 37.0.2.1
    f5dos
    • 4.9.0
    • 4.3.0 – ≤ 4.7.0
    • —
    • —
    f5nginx_gateway_fabric
    • 1.3.0 – ≤ 1.6.2
    • 2.0.0 – ≤ 2.6.3
    • —
    • —
    f5nginx_ingress_controller
    • 5.0.0 – ≤ 5.5.0
    • 3.5.0 – ≤ 3.7.2
    • 4.0.0 – ≤ 4.0.1
    • —
    • —
    • —
    f5nginx_instance_manager
    • 2.17.0 – ≤ 2.22.0
    • —
    f5nginx_open_source
    • 1.31.0 – ≤ 1.31.1
    • 1.0.0 – ≤ 1.30.2
    • —
    • —
    f5nginx_plus
    • r36
    • 37.0.0.1 – < 37.0.2.1
    • r33 – < r36
    • —
    • 37.0.2.1
    • r36
    f5waf
    • 4.10.0 – ≤ 4.16.0
    • 5.9.0 – ≤ 5.13.1
    • 5.2.0 – ≤ 5.8.0
    • —
    • —
    • —
    NGINXNGINX
    • Ingress Controller
    • Instance Manager
    • App Protect WAF
    • App Protect DoS
    • —
    • —
    • —
    • —
    NGINXNGINX Gateway Fabric
    • < 2.6.4
    • 2.6.4
    NGINXNGINX Open Source
    • < 1.30.3
    • < 1.31.2
    • 1.30.3
    • 1.31.2
    NGINXNGINX Plus
    • <R36 P6
    • < 37.0.2.1
    • —
    • 37.0.2.1
    Distribution and container packages (1)

    Downstream packages (e.g. Bitnami, Debian, Ubuntu, Red Hat). Versions refer to the distribution, not the vendor.

    Distribution and container packages
    Affected versionsFixed in
    bitnaminginx-gateway-fabric
    • 1.3.0
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebiannginxbookworm
    Linuxdebiannginxbullseye
    Linuxdebiannginxtrixie

    Weakness classes (CWE)

    • CWE-125Out-of-bounds Read

      Base

      The product reads data past the end, or before the beginning, of the intended buffer.

      Entry at MITRE CWE-125

    References & sources

    • my.f5.commanage/s/article/K000161585web, Vendor advisory
    • NVD (NIST)vuln/detail/CVE-2026-48142web

    Changes to this CVE

    Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

    1. Reanalysis by NVDNVD

      Product mapping changed:
      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Product configurationchanged
      OR *cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:*:*:*:* versions from (including) 4.0.0 up to (including) 4.0.1 *cpe:2.3:a:f5:nginx_gateway_fabric:*:*:*:*:*:*:*:* versions from (including) 1.3.0 up to (including) 1.6.2 *cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:*:*:*:* versions from (including) 3.5.0 up to (including) 3.7.2 *cpe:2.3:a:f5:dos:*:*:*:*:*:nginx:*:* versions from (including) 4.3.0 up to (including) 4.7.0 *cpe:2.3:a:f5:dos:4.9.0:*:*:*:*:nginx:*:* *cpe:2.3:a:f5:nginx_gateway_fabric:*:*:*:*:*:*:*:* versions from (including) 2.0.0 up to (including) 2.6.3 *cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:*:*:*:* versions from (including) 5.0.0 up to (including) 5.5.0 *cpe:2.3:a:f5:nginx_instance_manager:*:*:*:*:*:*:*:* versions from (including) 2.17.0 up to (including) 2.22.0 *cpe:2.3:a:f5:nginx_open_source:*:*:*:*:*:*:*:* versions from (including) 1.0.0 up to (including) 1.30.2 *cpe:2.3:a:f5:nginx_open_source:*:*:*:*:*:*:*:* versions from (including) 1.31.0 up to (including) 1.31.1 *cpe:2.3:a:f5:nginx_plus:*:*:*:*:*:*:*:* versions from (including) 37.0.0 up to (including) 37.0.1 *cpe:2.3:a:f5:nginx_plus:*:*:*:*:*:*:*:* versions from (including) r33 up to (including) r36 *cpe:2.3:a:f5:waf:*:*:*:*:*:nginx:*:* versions from (including) 4.10.0 up to (including) 4.16.0 *cpe:2.3:a:f5:waf:*:*:*:*:*:nginx:*:* versions from (including) 5.2.0 up to (including) 5.8.0 *cpe:2.3:a:f5:waf:*:*:*:*:*:nginx:*:* versions from (including) 5.9.0 up to (including) 5.13.1
      OR *cpe:2.3:a:f5:nginx_gateway_fabric:*:*:*:*:*:*:*:* versions from (including) 1.3.0 up to (including) 1.6.2 *cpe:2.3:a:f5:dos:*:*:*:*:*:nginx:*:* versions from (including) 4.3.0 up to (including) 4.7.0 *cpe:2.3:a:f5:dos:4.9.0:*:*:*:*:nginx:*:* *cpe:2.3:a:f5:nginx_gateway_fabric:*:*:*:*:*:*:*:* versions from (including) 2.0.0 up to (including) 2.6.3 *cpe:2.3:a:f5:nginx_instance_manager:*:*:*:*:*:*:*:* versions from (including) 2.17.0 up to (including) 2.22.0 *cpe:2.3:a:f5:nginx_open_source:*:*:*:*:*:*:*:* versions from (including) 1.0.0 up to (including) 1.30.2 *cpe:2.3:a:f5:nginx_open_source:*:*:*:*:*:*:*:* versions from (including) 1.31.0 up to (including) 1.31.1 *cpe:2.3:a:f5:waf:*:*:*:*:*:nginx:*:* versions from (including) 4.10.0 up to (including) 4.16.0 *cpe:2.3:a:f5:waf:*:*:*:*:*:nginx:*:* versions from (including) 5.2.0 up to (including) 5.8.0 *cpe:2.3:a:f5:waf:*:*:*:*:*:nginx:*:* versions from (including) 5.9.0 up to (including) 5.13.1 *cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:continuous_releases:*:*:* versions from (including) 3.5.0 up to (including) 3.7.2 *cpe:2.3:a:f5:nginx_plus:*:*:*:*:continuous_releases:*:*:* versions from (including) r33 up to (excluding) r36 *cpe:2.3:a:f5:nginx_plus:r36:-:*:*:continuous_releases:*:*:* *cpe:2.3:a:f5:nginx_plus:r36:p1:*:*:continuous_releases:*:*:* *cpe:2.3:a:f5:nginx_plus:r36:p2:*:*:continuous_releases:*:*:* *cpe:2.3:a:f5:nginx_plus:r36:p3:*:*:continuous_releases:*:*:* *cpe:2.3:a:f5:nginx_plus:r36:p4:*:*:continuous_releases:*:*:* *cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:continuous_releases:*:*:* versions from (including) 4.0.0 up to (including) 4.0.1 *cpe:2.3:a:f5:nginx_plus:*:*:*:*:long-term_support:*:*:* versions from (including) 37.0.0.1 up to (excluding) 37.0.2.1 *cpe:2.3:a:f5:nginx_plus:r36:p5:*:*:continuous_releases:*:*:* *cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:continuous_releases:*:*:* versions from (including) 5.0.0 up to (including) 5.5.0

      Source identifier: nvd@nist.gov

    2. Record modifiedCISA ADP

      CISA assessment (SSVC): exploitation: none known, automatable: no

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      SSVC assessmentadded
      —
      {"id":"CVE-2026-48142","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-06-17T15:42:46.410409Z"}

      Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

    3. Receivedf5.com

      CVSS V4.0: AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N

      CVSS V3.1: AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L

      Weakness type: CWE-125

      Description added or changed

      Show 6 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      NGINX Open Source, NGINX Plus
      Descriptionadded
      —
      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.
      CVSSadded
      —
      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
      CVSSadded
      —
      AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L
      Weakness type (CWE)added
      —
      CWE-125
      Referenceadded
      —
      https://my.f5.com/manage/s/article/K000161585

      Source identifier: f5sirt@f5.com

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