LowCVE-2026-47241

    Net::IMAP: Denial of Service via incomplete raw argument validation (CVE-2026-47241)

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

    What is affected, what to do

    Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to 0.6.5 and 0.5.15, several Net::IMAP commands accept a raw string argument which is only validated to prevent CRLF injection and then sent verbatim.

    Update Ruby Net-imap to version 0.5.15.

    Affected
    • Ruby Net-imap gte 0.6.0, < 0.6.4.1..*
    • Ruby Net-imap lt *..0.5.15
    Fixed in
    • Ruby Net-imap 0.5.15

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

    Metrics

    2.1

    Priority

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

    Source: NVD, CVSS v4

    2.1

    CVSS v4

    Severity Low on the scale from 0 to 10.

    Source: BSI, Red Hat, CVE.org, Msrc Update Guide, OSV

    0.4 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 32.2

    Show all metrics
    Severity
    Low
    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
    38.03 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
    2.1 Methodology
    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
    2.1
    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
    0.4 %
    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
    32.2
    Elevated — this CVE ranks above at least 10% of all CVEs scored today.
    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 · automatable · Technical impact: partial
    Source: CISA Vulnrichment, as of 23 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-162, CWE-182, CWE-186

    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

    Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to 0.6.5 and 0.5.15, several Net::IMAP commands accept a raw string argument which is only validated to prevent CRLF injection and then sent verbatim. If this string is derived from user-controlled input, an attacker can force the next command to be absorbed as a continuation of the first command. This will cause the first command to eventually fail, but also prevents it from returning until another command is sent (from another thread). That other command will not return until the connection is closed. This vulnerability is fixed in 0.6.5 and 0.5.15.

    Source: BSI WID Portal, BSI CSAF, redhat_csaf, NVD (NIST), Microsoft Security Update Guide, OSV (Open Source Vulnerabilities), 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
    rubynet-imap
    • ≥ 0.6.0, < 0.6.4.1
    • < 0.5.15
    • —
    • 0.5.15
    Open SourceRuby
    • < 3.3.12
    • 3.3.12
    rubygemsnet-imap
    • 0.5.0
    • 0.4.0
    • 0.3.5
    • 0.2.2
    • 0.4.12
    • 0.2.5
    • 0.5.5
    • 0.5.7
    • 0.4.25
    • 0.3.6
    • 0.1.1
    • 0.4.6
    • 0.5.2
    • 0.4.23
    • 0.5.8
    • 0.5.4
    • 0.3.2
    • 0.3.7
    • 0.6.1
    • 0.2.4
    • 0.4.4
    • 0.4.21
    • 0.2.0
    • 0.4.9.1
    • 0.5.10
    • 0.6.0
    • 0.4.7
    • 0.4.2
    • 0.4.9
    • 0.3.8
    • 0.5.12
    • 0.3.4
    • 0.3.10
    • 0.5.6
    • 0.3.9
    • 0.3.3
    • 0.5.14
    • 0.4.17
    • 0.4.5
    • 0.4.1
    • 0.4.8
    • 0.2.3
    • 0.5.3
    • 0.5.1
    • 0.3.4.1
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    Vendors and products

    Weakness classes (CWE)

    • CWE-162Improper Neutralization of Trailing Special Elements

      Variant

      The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes trailing special elements that could be interpreted in unexpected ways when they are sent to a downstream component.

      Entry at MITRE CWE-162

    • CWE-182Collapse of Data into Unsafe Value

      Base

      The product filters data in a way that causes it to be reduced or "collapsed" into an unsafe value that violates an expected security property.

      Entry at MITRE CWE-182

    • CWE-186Overly Restrictive Regular Expression

      Base

      A regular expression is overly restrictive, which prevents dangerous values from being detected.

      Entry at MITRE CWE-186

    References & sources

    • github.comruby/net-imap/security/advisories/GHSA-c4fp-cxrr-mj66web, x_refsource_CONFIRM
    • NVD (NIST)vuln/detail/CVE-2026-47241advisory
    • github.comruby/net-imappackage
    • github.comruby/net-imap/releases/tag/v0.6.4.1web
    • github.comrubysec/ruby-advisory-db/blob/master/gems/net-imap/CVE-2026-472…web
    • CVE.org (MITRE)CVERecord?id=CVE-2026-47241web

    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. ReceivedGitHub

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

      Weakness type: CWE-162, CWE-182, CWE-186

      Description added or changed

      Show 7 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      net-imap
      Descriptionadded
      —
      Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to 0.6.5 and 0.5.15, several Net::IMAP commands accept a raw string argument which is only validated to prevent CRLF injection and then sent verbatim. If this string is derived from user-controlled input, an attacker can force the next command to be absorbed as a continuation of the first command. This will cause the first command to eventually fail, but also prevents it from returning until another command is sent (from another thread). That other command will not return until the connection is closed. This vulnerability is fixed in 0.6.5 and 0.5.15.
      CVSSadded
      —
      AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/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
      Weakness type (CWE)added
      —
      CWE-162
      Weakness type (CWE)added
      —
      CWE-182
      Weakness type (CWE)added
      —
      CWE-186
      Referenceadded
      —
      https://github.com/ruby/net-imap/security/advisories/GHSA-c4fp-cxrr-mj66

      Source identifier: security-advisories@github.com

    One NVD translation into another language is hidden.

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