MediumCVE-2025-3576

    Krb5: kerberos rc4-hmac-md5 checksum vulnerability enabling message spoofing via md5 collisions (CVE-2025-3576)

    Published Last modified Sources: BSI, Siemens ProductCERT, Debian LTS, SUSE, Msrc Update Guide, CVE.org, EUVD

    What is affected, what to do

    A vulnerability in the MIT Kerberos implementation allows GSSAPI-protected messages using RC4-HMAC-MD5 to be spoofed due to weaknesses in the MD5 checksum design. If RC4 is preferred over stronger encryption types, an attacker could exploit MD5 collisions to forge message integrity codes.

    Update Krb5 to version 1.22, Red Hat Enterprise Linux 10 to version 0:1.21.3-8.el10_0, Red Hat Enterprise Linux 8 to version 0:1.18.2-32.el8_10.

    Affected
    • Krb5 lt *..1.22
    • Red Hat Enterprise Linux 10 lt *..0:1.21.3-8.el10_0
    • Red Hat Enterprise Linux 8 lt *..0:1.18.2-32.el8_10
    • Red Hat Enterprise Linux 8.2 Advanced Update Support lt *..0:1.17-19.el8_2.3
    • Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support lt *..0:1.18.2-9.el8_4.3
    • Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On lt *..0:1.18.2-9.el8_4.3
    • Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support lt *..0:1.18.2-16.el8_6.4
    • Red Hat Enterprise Linux 8.6 Telecommunications Update Service lt *..0:1.18.2-16.el8_6.4
    • Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions lt *..0:1.18.2-16.el8_6.4
    • Red Hat Enterprise Linux 8.8 Telecommunications Update Service lt *..0:1.18.2-26.el8_8.5
    • Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions lt *..0:1.18.2-26.el8_8.5
    • Red Hat Enterprise Linux 9 lt *..0:1.21.1-8.el9_6
    • Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions lt *..0:1.19.1-16.el9_0.4
    • Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions lt *..0:1.20.1-9.el9_2.3
    • Red Hat Enterprise Linux 9.4 Extended Update Support lt *..0:1.21.1-2.el9_4.2
    • Red Hat Discovery 2 lt *..2.0.0-1752592913
    Fixed in
    • Krb5 1.22
    • Red Hat Enterprise Linux 10 0:1.21.3-8.el10_0
    • Red Hat Enterprise Linux 8 0:1.18.2-32.el8_10
    • Red Hat Enterprise Linux 8.2 Advanced Update Support 0:1.17-19.el8_2.3
    • Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support 0:1.18.2-9.el8_4.3
    • Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On 0:1.18.2-9.el8_4.3
    • Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support 0:1.18.2-16.el8_6.4
    • Red Hat Enterprise Linux 8.6 Telecommunications Update Service 0:1.18.2-16.el8_6.4
    • Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions 0:1.18.2-16.el8_6.4
    • Red Hat Enterprise Linux 8.8 Telecommunications Update Service 0:1.18.2-26.el8_8.5
    • Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions 0:1.18.2-26.el8_8.5
    • Red Hat Enterprise Linux 9 0:1.21.1-8.el9_6
    • Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions 0:1.19.1-16.el9_0.4
    • Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions 0:1.20.1-9.el9_2.3
    • Red Hat Enterprise Linux 9.4 Extended Update Support 0:1.21.1-2.el9_4.2
    • Red Hat Discovery 2 2.0.0-1752592913

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    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: BSI, Siemens ProductCERT, Debian LTS, SUSE, Msrc Update Guide, CVE.org, EUVD

    0.4 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 28.5

    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
    44.63 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
    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
    28.5
    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
    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-328

    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 vulnerability in the MIT Kerberos implementation allows GSSAPI-protected messages using RC4-HMAC-MD5 to be spoofed due to weaknesses in the MD5 checksum design. If RC4 is preferred over stronger encryption types, an attacker could exploit MD5 collisions to forge message integrity codes. This may lead to unauthorized message tampering.

    Source: BSI WID Portal, BSI CSAF, siemens_advisory, Debian LTS Advisories, suse_csaf, Microsoft Security Update Guide, cvelistv5, NVD (NIST), CVE.org (MITRE), ENISA EUVD

    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
    —krb5
    • < 1.22
    • 1.22
    Red HatRed Hat Discovery 2
    • < 2.0.0-1752592913
    • 2.0.0-1752592913
    Red HatRed Hat Enterprise Linux 10
    • < 0:1.21.3-8.el10_0
    • 0:1.21.3-8.el10_0
    Red HatRed Hat Enterprise Linux 6
    • —
    • —
    Red HatRed Hat Enterprise Linux 7
    • —
    • —
    Red HatRed Hat Enterprise Linux 8
    • < 0:1.18.2-32.el8_10
    • 0:1.18.2-32.el8_10
    Red HatRed Hat Enterprise Linux 8.2 Advanced Update Support
    • < 0:1.17-19.el8_2.3
    • 0:1.17-19.el8_2.3
    Red HatRed Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
    • < 0:1.18.2-9.el8_4.3
    • 0:1.18.2-9.el8_4.3
    Red HatRed Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On
    • < 0:1.18.2-9.el8_4.3
    • 0:1.18.2-9.el8_4.3
    Red HatRed Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
    • < 0:1.18.2-16.el8_6.4
    • 0:1.18.2-16.el8_6.4
    Red HatRed Hat Enterprise Linux 8.6 Telecommunications Update Service
    • < 0:1.18.2-16.el8_6.4
    • 0:1.18.2-16.el8_6.4
    Red HatRed Hat Enterprise Linux 8.6 Update Services for SAP Solutions
    • < 0:1.18.2-16.el8_6.4
    • 0:1.18.2-16.el8_6.4
    Red HatRed Hat Enterprise Linux 8.8 Telecommunications Update Service
    • < 0:1.18.2-26.el8_8.5
    • 0:1.18.2-26.el8_8.5
    Red HatRed Hat Enterprise Linux 8.8 Update Services for SAP Solutions
    • < 0:1.18.2-26.el8_8.5
    • 0:1.18.2-26.el8_8.5
    Red HatRed Hat Enterprise Linux 9
    • < 0:1.21.1-8.el9_6
    • 0:1.21.1-8.el9_6
    Red HatRed Hat Enterprise Linux 9.0 Update Services for SAP Solutions
    • < 0:1.19.1-16.el9_0.4
    • 0:1.19.1-16.el9_0.4
    Red HatRed Hat Enterprise Linux 9.2 Update Services for SAP Solutions
    • < 0:1.20.1-9.el9_2.3
    • 0:1.20.1-9.el9_2.3
    Red HatRed Hat Enterprise Linux 9.4 Extended Update Support
    • < 0:1.21.1-2.el9_4.2
    • 0:1.21.1-2.el9_4.2
    Red HatRed Hat OpenShift Container Platform 4
    • —
    • —
    XeroxFreeFlow Print Server
    • v7
    • v2
    • —
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebiankrb5bullseye

    Weakness classes (CWE)

    • CWE-328Use of Weak Hash

      Base

      The product uses an algorithm that produces a digest (output value) that does not meet security expectations for a hash function that allows an adversary to reasonably determine the original input (preimage attack), find another input that can produce the same hash (2nd preimage attack), or find multiple inputs that evaluate to the same hash (birthday attack).

      Entry at MITRE CWE-328

    References & sources

    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. Record modifiedRed Hat

      Show 29 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2025/3xxx/CVE-2025-3576.json">CVE-2025-3576</a>
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2025:11487
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2025:13664
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2025:13777
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2025:15000
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2025:15001
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2025:15002
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2025:15003
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2025:15004
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2025:8411
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2025:9418
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2025:9430
      Referenceadded
      —
      https://access.redhat.com/security/cve/CVE-2025-3576
      Referenceadded
      —
      https://bugzilla.redhat.com/show_bug.cgi?id=2359465
      Referenceadded
      —
      https://web.mit.edu/kerberos/krb5-1.22/krb5-1.22.html
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2025:11487
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2025:13664
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2025:13777
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2025:15000
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2025:15001
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2025:15002
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2025:15003
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2025:15004
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2025:8411
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2025:9418
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2025:9430
      —
      Referenceremoved
      https://access.redhat.com/security/cve/CVE-2025-3576
      —
      Referenceremoved
      https://bugzilla.redhat.com/show_bug.cgi?id=2359465
      —
      Referenceremoved
      https://web.mit.edu/kerberos/krb5-1.22/krb5-1.22.html
      —

      Source identifier: secalert@redhat.com

    2. Record modifiedCVE Program

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://lists.debian.org/debian-lts-announce/2025/05/msg00047.html
      Referenceremoved
      https://lists.debian.org/debian-lts-announce/2025/05/msg00047.html
      —

      Source identifier: af854a3a-2127-422b-91ae-364da2661108

    3. Record modifiedSiemens ADP

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://cert-portal.siemens.com/productcert/html/ssa-577017.html
      Referenceremoved
      https://cert-portal.siemens.com/productcert/html/ssa-577017.html
      —

      Source identifier: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e

    4. Record modifiedRed Hat

      1 individual change: Affected versions (publisher)

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)changed
      …, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8 (+17)
      …, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8 (+17)

      Source identifier: secalert@redhat.com

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