MediumCVE-2023-4806

    Glibc: potential use-after-free in getaddrinfo() (CVE-2023-4806)

    Published Sources: Siemens ProductCERT, CVE.org

    What is affected, what to do

    A flaw has been identified in glibc. In an extremely rare situation, the getaddrinfo function may access memory that has been freed, resulting in an application crash.

    Update Red Hat Enterprise Linux 8 to version 0:2.28-225.el8_8.6, Red Hat Enterprise Linux 8.6 Extended Update Support to version 0:2.28-189.8.el8_6, Red Hat Enterprise Linux 9 to version 0:2.34-60.el9_2.7.

    Affected
    • Red Hat Enterprise Linux 8 lt *..0:2.28-225.el8_8.6
    • Red Hat Enterprise Linux 8.6 Extended Update Support lt *..0:2.28-189.8.el8_6
    • Red Hat Enterprise Linux 9 lt *..0:2.34-60.el9_2.7
    • Red Hat Virtualization 4 for Red Hat Enterprise Linux 8 lt *..0:2.28-189.8.el8_6
    Fixed in
    • Red Hat Enterprise Linux 8 0:2.28-225.el8_8.6
    • Red Hat Enterprise Linux 8.6 Extended Update Support 0:2.28-189.8.el8_6
    • Red Hat Enterprise Linux 9 0:2.34-60.el9_2.7
    • Red Hat Virtualization 4 for Red Hat Enterprise Linux 8 0:2.28-189.8.el8_6

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

    Metrics

    5.9

    Priority

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

    Source: NVD, CVSS v3

    5.9

    CVSS v3

    Severity Medium on the scale from 0 to 10.

    Source: Siemens ProductCERT, CVE.org

    1.6 %

    EPSS score

    Moderate — model estimates 1-10% exploitation likelihood.

    Source: FIRST EPSS, percentile 75.8

    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
    78.87 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
    5.9 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
    5.9
    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
    1.6 %
    Moderate — model estimates 1-10% 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
    75.8
    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
    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-416

    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

    A flaw has been identified in glibc. In an extremely rare situation, the getaddrinfo function may access memory that has been freed, resulting in an application crash. This issue is only exploitable when a NSS module implements only the _nss_*_gethostbyname2_r and _nss_*_getcanonname_r hooks without implementing the _nss_*_gethostbyname3_r hook. The resolved name should return a large number of IPv6 and IPv4, and the call to the getaddrinfo function should have the AF_INET6 address family with AI_CANONNAME, AI_ALL and AI_V4MAPPED as flags.

    Source: siemens_advisory, cvelistv5, NVD (NIST)

    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
    Red HatRed Hat Enterprise Linux 6
    • —
    • —
    Red HatRed Hat Enterprise Linux 7
    • —
    • —
    Red HatRed Hat Enterprise Linux 8
    • < 0:2.28-225.el8_8.6
    • 0:2.28-225.el8_8.6
    Red HatRed Hat Enterprise Linux 8.6 Extended Update Support
    • < 0:2.28-189.8.el8_6
    • 0:2.28-189.8.el8_6
    Red HatRed Hat Enterprise Linux 9
    • < 0:2.34-60.el9_2.7
    • 0:2.34-60.el9_2.7
    Red HatRed Hat Virtualization 4 for Red Hat Enterprise Linux 8
    • < 0:2.28-189.8.el8_6
    • 0:2.28-189.8.el8_6
    gnuglibc
    • 2.33
    • —
    redhatcodeready_linux_builder_eus
    • 9.2
    • —
    redhatcodeready_linux_builder_eus_for_power_little_endian
    • 9.0_ppc64le
    • —
    redhatcodeready_linux_builder_eus_for_power_little_endian_eus
    • 9.2_ppc64le
    • —
    redhatcodeready_linux_builder_for_arm64
    • 9.0_aarch64
    • —
    redhatcodeready_linux_builder_for_arm64_eus
    • 9.2_aarch64
    • —
    redhatcodeready_linux_builder_for_ibm_z_systems
    • 9.0_s390x
    • —
    redhatcodeready_linux_builder_for_ibm_z_systems_eus
    • 9.2_s390x
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxredhatenterprise_linux7.0
    Linuxredhatenterprise_linux8.0
    Linuxredhatenterprise_linux9.0
    Linuxredhatenterprise_linux_eus8.8
    Linuxredhatenterprise_linux_eus9.2
    Linuxredhatenterprise_linux_for_arm_649.0_aarch64
    Linuxredhatenterprise_linux_for_arm_64_eus9.2_aarch64
    Linuxredhatenterprise_linux_for_ibm_z_systems8.0_s390x
    Linuxredhatenterprise_linux_for_ibm_z_systems_eus8.8_s390x
    Linuxredhatenterprise_linux_for_ibm_z_systems_eus_s390x9.2
    Linuxredhatenterprise_linux_for_ibm_z_systems_s390x9.2
    Linuxredhatenterprise_linux_for_power_little_endian8.0_ppc64le
    Linuxredhatenterprise_linux_for_power_little_endian9.2_ppc64le
    Linuxredhatenterprise_linux_for_power_little_endian_eus8.8_ppc64le
    Linuxredhatenterprise_linux_for_power_little_endian_eus9.2_ppc64le
    Linuxredhatenterprise_linux_server_aus9.2
    Linuxredhatenterprise_linux_server_for_power_little_endian_update_services_for_sap_solutions9.2_ppc64le
    Linuxredhatenterprise_linux_tus8.8
    Otherfedoraprojectfedora37
    Otherfedoraprojectfedora38
    Otherfedoraprojectfedora39

    Weakness classes (CWE)

    • CWE-416Use After Free

      Variant

      The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

      Entry at MITRE CWE-416

    References & sources

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    Badge preview for CVE-2023-4806
    <a href="https://intel.neosec.eu/en/cve/CVE-2023-4806"><img src="https://intel.neosec.eu/badge/cve/CVE-2023-4806.svg?lang=en" alt="CVE-2023-4806 – NEOSEC Intel" height="20"></a>