MediumCVE-2026-16552

    Red Hat: Link Following (CVE-2026-16552)

    Published Last modified Sources: BSI, CVE.org

    What is affected, what to do

    A flaw was found in systemd-tmpfiles. When processing a tmpfiles.d configuration entry that writes to a file, systemd-tmpfiles can follow a symbolic link placed by an unprivileged local user, and an existing safety check does not detect this specific case because it always treats transitions away from the root user as safe.

    The available sources name no fixed version. Check the vendor guidance in the references below.

    Affected
    • open source Systemd range_unparsed *..tmpfiles <commit b9ef5951f8f9e156479494fdb9ca6274cb3d3c53

    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 v3

    6.3

    CVSS v3

    Severity Medium on the scale from 0 to 10.

    Source: BSI, CVE.org

    —

    EPSS score

    No value is available for this vulnerability.

    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
    52.52 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
    6.3
    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-59

    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 was found in systemd-tmpfiles. When processing a tmpfiles.d configuration entry that writes to a file, systemd-tmpfiles can follow a symbolic link placed by an unprivileged local user, and an existing safety check does not detect this specific case because it always treats transitions away from the root user as safe. On systems where a tmpfiles.d configuration targets a path an unprivileged user can influence, this could allow that user to redirect a privileged systemd-tmpfiles write to a file of their choosing, though the content written remains determined by the existing configuration rather than by the unprivileged user. The highest threat from this vulnerability is to integrity.

    Source: BSI CSAF, BSI WID Portal, 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
    Red HatRed Hat Enterprise Linux 10
    • —
    • —
    Red HatRed Hat Enterprise Linux 7
    • —
    • —
    Red HatRed Hat Enterprise Linux 8
    • —
    • —
    Red HatRed Hat Enterprise Linux 9
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    Red HatRed Hat Hardened Images
    • —
    • —
    Red HatRed Hat OpenShift Container Platform 4
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    Open Sourcesystemd
    • tmpfiles <commit b9ef5951f8f9e156479494fdb9ca6274cb3d3c53
    • —

    Vendors and products

    Weakness classes (CWE)

    • CWE-59Improper Link Resolution Before File Access ('Link Following')

      Base

      The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

      Entry at MITRE CWE-59

    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. Rejected98a521c5…

    2. Record modified98a521c5…

      CVSS V3.1: before Red Hat, Inc.: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H, after —

      Description added or changed

      Show 8 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionchanged
      A flaw was found in systemd-tmpfiles. When processing a tmpfiles.d configuration entry that writes to a file, systemd-tmpfiles can follow a symbolic link placed by an unprivileged local user, and an existing safety check does not detect this specific case because it always treats transitions away from the root user as safe. On systems where a tmpfiles.d configuration targets a path an unprivileged user can influence, this could allow that user to redirect a privileged systemd-tmpfiles write to a file of their choosing, though the content written remains determined by the existing configuration rather than by the unprivileged user. The highest threat from this vulnerability is to integrity.
      Rejected reason: The reported issue is invalid, as it requires root privileges to reproduce, and it is out of scope of the threat model of the affected component.
      CVSSremoved
      Red Hat, Inc.: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H
      —
      Weakness type (CWE)removed
      Red Hat, Inc.: CWE-59
      —
      Referenceremoved
      Red Hat, Inc.: https://access.redhat.com/security/cve/CVE-2026-16552
      —
      Referenceremoved
      Red Hat, Inc.: https://bugzilla.redhat.com/show_bug.cgi?id=2506073
      —
      Referenceremoved
      Red Hat, Inc.: https://github.com/systemd/systemd/blob/b9ef5951f8f9e156479494fdb9ca6274cb3d3c53/src/basic/chase.c
      —
      Referenceremoved
      Red Hat, Inc.: https://github.com/systemd/systemd/blob/b9ef5951f8f9e156479494fdb9ca6274cb3d3c53/src/tmpfiles/tmpfiles.c
      —
      Affected versions (publisher)removed
      Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8 (+3)
      —

      Source identifier: 98a521c5-3a3e-4e2b-bc27-002067e0463c

    3. 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-2026-16552","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-07-22T16:07:52.239845Z"}

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

    4. ReceivedRed Hat

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

      Weakness type: CWE-59

      Description added or changed

      Show 8 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8 (+3)
      Descriptionadded
      —
      A flaw was found in systemd-tmpfiles. When processing a tmpfiles.d configuration entry that writes to a file, systemd-tmpfiles can follow a symbolic link placed by an unprivileged local user, and an existing safety check does not detect this specific case because it always treats transitions away from the root user as safe. On systems where a tmpfiles.d configuration targets a path an unprivileged user can influence, this could allow that user to redirect a privileged systemd-tmpfiles write to a file of their choosing, though the content written remains determined by the existing configuration rather than by the unprivileged user. The highest threat from this vulnerability is to integrity.
      CVSSadded
      —
      AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H
      Weakness type (CWE)added
      —
      CWE-59
      Referenceadded
      —
      https://access.redhat.com/security/cve/CVE-2026-16552
      Referenceadded
      —
      https://bugzilla.redhat.com/show_bug.cgi?id=2506073
      Referenceadded
      —
      https://github.com/systemd/systemd/blob/b9ef5951f8f9e156479494fdb9ca6274cb3d3c53/src/basic/chase.c
      Referenceadded
      —
      https://github.com/systemd/systemd/blob/b9ef5951f8f9e156479494fdb9ca6274cb3d3c53/src/tmpfiles/tmpfiles.c

      Source identifier: secalert@redhat.com

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