CriticalCVE-2026-54420

    LiteSpeed cPanel Plugin UNIX Symbolic Link (Symlink) Following Vulnerability (CVE-2026-54420)

    Published Last modified In CISA KEV since Sources: CVE.org

    What is affected, what to do

    LiteSpeed cPanel plugin before 2.4.8 (as distributed in LiteSpeed WHM PlugIn before 5.3.2.0) mishandles symlinks provided by a user with FTP or web shell access on a shared hosting server running CloudLinux/CageFS, as exploited in the wild in May 2026.

    The vulnerability is being actively exploited; treat it as a priority. Update LiteSpeed Technologies cPanel Plugin to version 2.4.8. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • LiteSpeed Technologies cPanel Plugin lt 2.3..2.4.8
    Fixed in
    • LiteSpeed Technologies cPanel Plugin 2.4.8

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

    Metrics

    8.5

    Priority

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

    Source: NVD, CVSS v3

    8.5

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: CVE.org

    1.4 %

    EPSS score

    Moderate — model estimates 1-10% exploitation likelihood.

    Source: FIRST EPSS, percentile 73.1

    Show all metrics
    Severity
    Critical
    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
    204.11 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
    actively exploitedSource: VulnCheck KEV (opens in a new tab) How we classify
    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
    8.5 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
    8.5
    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
    1.4 %
    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
    73.1
    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
    Actively exploited
    Published
    In CISA KEV since

    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
    CISA assessment (SSVC)
    Exploitation: active · not automatable · Technical impact: total
    Source: CISA Vulnrichment, as of 15 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-61

    Response and mitigation

    Why act now?

    Prioritisation rationale

    This sits on KEV because attackers who already hold an FTP account or web shell can abuse crafted symlinks to break out of CageFS tenant isolation. The vector describes a network-reachable attack needing only low privileges, with higher complexity, changed scope and full confidentiality, integrity and availability impact. Typical victims are shared-hosting providers and web agencies, where one compromised WordPress site becomes a pivot into every tenant on the box. Broad exploitation likelihood is rated moderate and CISA lists no known ransomware use. For anyone running cPanel/CloudLinux with LiteSpeed, though, treat this as high priority with a 24-72 h patch window. Organisations that don't operate shared hosting are exposed only through sites hosted on such platforms, so ask your hoster directly for their patch status.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Patch now: Upgrade the LiteSpeed WHM PlugIn to 5.3.2.0 or later, which ships LiteSpeed cPanel Plugin 2.4.8 or later. Verify the installed version in WHM afterwards. Use the update path (WHM UI or CLI) given in the vendor documentation.
      • Pull the feature if you can't patch yet: Remove the LiteSpeed cPanel plugin from all feature lists in WHM Feature Manager. This stops tenant accounts from invoking the vulnerable code path.
      • Triage attacker entry points: List all accounts with FTP or shell access on CloudLinux/CageFS hosts. Run ImunifyAV, Imunify360 or Maldet across public_html to find web shells. Suspend suspicious accounts pending review.
      • Sweep for malicious symlinks: Run find /home*/ -xdev -type l \( -lname '/etc/*' -o -lname '/root/*' -o -lname '/home*/*' -o -lname '/var/cpanel/*' \) -ls. Treat any tenant-owned link that points into system paths or another tenant's home as an escape attempt.
      • Rotate secrets on suspected compromise: Exploitation breaks tenant isolation (changed scope), so rotation must cover more than the affected tenant. Rotate DB credentials stored in app configs (wp-config.php, .env), WHM API tokens, root credentials and SSH host keys on affected servers.

    2. Runbook step 2

      Mitigation layers

      • Kernel hardening (CloudLinux SecureLinks): Set fs.enforce_symlinksifowner=1, fs.protected_symlinks=1 and fs.protected_hardlinks=1 via sysctl and persist them in /etc/sysctl.d/. This stops privileged processes from following links owned by other users.
      • Web server config: Allow SymLinksIfOwnerMatch instead of FollowSymLinks in LiteSpeed/Apache. Enable cPanel's "Symlink Race Condition Protection". Lock AllowOverride so tenants can't re-enable link following via .htaccess.
      • Least privilege: Disable plain FTP and offer only SFTP inside CageFS jails. Grant shell access (jailshell/noshell) on request only. Remove dormant FTP sub-accounts.
      • Network segmentation: Restrict WHM (2086/2087) and admin access to cPanel (2082/2083) to management networks or VPN. Expose FTP (21) and the passive port range only where customers genuinely need it.
      • WAF/endpoint: Tighten ModSecurity/Imunify360 rules against web-shell uploads, for example by blocking .php, .phtml and archive uploads into upload directories. Enable Proactive Defense to block PHP symlink() and exec() from web contexts. Also set disable_functions = symlink,link,exec,shell_exec,system,passthru in the tenant-wide php.ini.

    3. Runbook step 3

      Detection rules

      • auditd – symlink creation: -a always,exit -F arch=b64 -S symlink,symlinkat -F auid>=1000 -F auid!=unset -k cve_2026_54420. Alert when a tenant UID creates a link targeting /etc/, /root/, /var/cpanel/ or another /home/<user>/.
      • auditd – privileged reads: Add watches on sensitive files (-w /etc/shadow -p r -k shadow_read, plus /root/.ssh/ and /var/cpanel/users/). Escalate when the process tree traces back to cPanel/LiteSpeed plugin processes (cpsrvd parent or plugin scripts) and follows a symlink event from the same tenant.
      • Web access logs: Hunt for POSTs to freshly dropped PHP files under wp-content/uploads/, tmp/ or cache/, and for parameters such as cmd=, c= or exec=. Example KQL: WebLogs | where Method == "POST" and UriPath matches regex @"/uploads/.*\.php$" | summarize count() by Host, UriPath, ClientIP.
      • FTP logs (Pure-FTPd/ProFTPD): Look for archive uploads later extracted via cPanel File Manager or the plugin, and for FTP logins from unusual geographies. Correlate with hits from the symlink sweep.
      • EDR process ancestry: As a Sigma shape: ParentImage|contains: 'cpanel' AND User: root AND CommandLine|contains: '/home/', followed by file access outside the triggering tenant's home directory.

    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
    Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
    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
    Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
    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

    LiteSpeed cPanel plugin before 2.4.8 (as distributed in LiteSpeed WHM PlugIn before 5.3.2.0) mishandles symlinks provided by a user with FTP or web shell access on a shared hosting server running CloudLinux/CageFS, as exploited in the wild in May 2026.

    Source: cvelistv5, CISA KEV Catalog, NVD (NIST), CVE.org (MITRE)

    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
    LiteSpeed TechnologiescPanel Plugin
    • 2.3 – < 2.4.8
    • 2.4.8
    litespeedtechlitespeed_cpanel_plugin
    • < 2.4.8
    • 2.4.8
    litespeedtechlitespeed_whm_plugin
    • < 5.3.2.0
    • 5.3.2.0

    Vendors and products

    Weakness classes (CWE)

    • CWE-61UNIX Symbolic Link (Symlink) Following

      Compound

      The product, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files.

      Entry at MITRE CWE-61

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    CISA KEV CatalogCISA Known Exploited Vulnerability (opens in a new tab)cisa.govactively exploited
    PoC-in-GitHub (nomi-sec)CVE-2026-54420-LiteSpeed-Symlink-Exploit (opens in a new tab)github.comPoC (publicly reported)reported, not verified
    PoC-in-GitHub (nomi-sec)CVE-2026-54420 (opens in a new tab)github.comPoC (publicly reported)reported, not verified

    References & sources

    • litespeedtech.comproducts/litespeed-web-server/control-panel-support/cpanel
    • blog.litespeedtech.com2026/06/01/security-update-for-litespeed-cpanel-plugin-2
    • cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2026-54420government-resource

    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. CISA KEV entry updated9119a7d8…

      4 individual changes: Date Added, Due Date, Required Action, Vulnerability Name

      Show 4 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Date Addedadded
      —
      2026-06-15
      Due Dateadded
      —
      2026-06-15
      Required Actionadded
      —
      2026-06-15
      Vulnerability Nameadded
      —
      2026-06-15

      Source identifier: 9119a7d8-5eab-497f-8521-727c672e3725

    2. Record modifiedCISA ADP

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-54420

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

    3. Initial analysis by NVDNVD

      Show 3 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Product configurationadded
      —
      OR *cpe:2.3:a:litespeedtech:litespeed_cpanel_plugin:*:*:*:*:*:*:*:* versions up to (excluding) 2.4.8 *cpe:2.3:a:litespeedtech:litespeed_whm_plugin:*:*:*:*:*:*:*:* versions up to (excluding) 5.3.2.0
      Reference typeadded
      —
      MITRE: https://blog.litespeedtech.com/2026/06/01/security-update-for-litespeed-cpanel-plugin-2/ Types: Vendor Advisory
      Reference typeadded
      —
      MITRE: https://www.litespeedtech.com/products/litespeed-web-server/control-panel-support/cpanel Types: Product

      Source identifier: nvd@nist.gov

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