CriticalCVE-2026-56291

    Joomla Extension - balbooa.com - Unauthenticated file upload in Balbooa Forms extension < 2.4.1 (CVE-2026-56291)

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

    What is affected, what to do

    A critical unrestricted file upload vulnerability in balbooa forms allows unauthenticated remote attackers to upload arbitrary files, leading to full remote code execution on the target system. No user interaction or prior authentication is required, making exploitation trivial for any network-reachable instance. The vulnerability is actively exploited in the wild and has been added to the CISA Known Exploited Vulnerabilities catalog, confirming real-world attack activity. Organizations using balbooa forms should immediately verify exposure and apply available patches or mitigations without delay. Given the complete compromise of confidentiality, integrity, and availability, this warrants the highest remediation priority.

    The vulnerability is being actively exploited; treat it as a priority. Update forms to version 2.4.1. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • balbooa.com Balbooa Forms extension for Joomla eq 1.0-2.4.0..1.0-2.4.0

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

    Metrics

    10.0

    Priority

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

    Source: NVD, CVSS v4

    9.8

    CVSS v3

    Severity Critical on the scale from 0 to 10.

    Source: CVE.org

    14.9 %

    EPSS score

    Elevated — model estimates 10-50% exploitation likelihood.

    Source: FIRST EPSS, percentile 96.7

    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
    245.26 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
    10.0 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
    9.8
    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
    10.0
    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“.

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    14.9 %
    Elevated — model estimates 10-50% 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
    96.7
    Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
    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
    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-434

    Response and mitigation

    Why act now?

    Prioritisation rationale

    This flaw is reachable over the network with no authentication and no user interaction, and exploitation is trivial. A single upload request yields a web shell and full code execution as the web server user, and exploitation likelihood is very high. CISA does not flag ransomware use, but typical outcomes are persistent web shells, SEO spam and defacement, theft of form submissions and DB credentials, and pivoting out of the DMZ. Treat every internet-facing Joomla instance with Balbooa Forms as top priority: patch and hunt today. Internal-only instances come immediately after.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Inventory: Identify every Joomla site running Balbooa Forms (Backend → System → Manage Extensions, or on disk: administrator/components/com_baforms/). All versions 1.0 through 2.4.0 are vulnerable.
      • Patch: Upgrade Balbooa Forms to 2.4.1 or later. Clear the Joomla cache and confirm the installed version in the backend.
      • If you cannot update right away: Disable or uninstall the extension in the Joomla backend. Alternatively, take public form pages offline until the patch is in place.
      • Hunt for compromise: Search the webroot for recently created executable files, e.g. find /var/www -type f \( -iname "*.php*" -o -iname "*.phtml" -o -iname "*.phar" \) -newermt "2026-06-01". Focus on upload and media directories (images/, media/, tmp/, the extension's upload path).
      • If you find a web shell: Isolate the host and capture a forensic image before you clean anything. Then rotate all credentials: Joomla admin accounts, the DB password in configuration.php, $secret, FTP/SSH keys, and any API tokens stored in the config.
      • Check reporting obligations: For a confirmed breach, track the NIS2 deadlines (early warning to BSI/the competent CSIRT within 24 h). Also assess GDPR impact, since form submissions usually contain personal data.

    2. Runbook step 2

      Mitigation layers

      • WAF/reverse proxy: Deny multipart POSTs to option=com_baforms whose filenames end in .php, .phtml, .phar, .php5, .php7, .pht or .shtml. Also catch double extensions such as shell.php.jpg. A ModSecurity rule idea: ARGS:option "@contains com_baforms" chained with FILES "@rx \.(ph(p[0-9]?|tml|ar|t)|shtml)$" → deny.
      • Web server hardening: Block PHP execution in upload directories. For Apache: <FilesMatch "\.(php|phtml|phar)$"> Require all denied </FilesMatch> in images/ and media/. For nginx: location ~* ^/(images|media|tmp)/.*\.php$ { deny all; }.
      • Filesystem permissions: Keep the webroot read-only for the web server user (www-data, apache) except for the upload paths that strictly need write access. Where possible, mount the Joomla tree read-only and deploy updates through a pipeline.
      • PHP configuration: Set disable_functions = exec,passthru,shell_exec,system,proc_open,popen and restrict open_basedir to the webroot. This blunts what an uploaded shell can do.
      • Segmentation: Restrict web server egress to required destinations only, such as update servers. Allow DB access from the web segment only. Protect /administrator/ with an IP allowlist or VPN.

    3. Runbook step 3

      Detection rules

      • Web access logs: Look for POSTs containing option=com_baforms from unfamiliar sources, especially when followed by a GET to a new .php file under an upload or media path. SPL example: index=web method=POST uri_query="*com_baforms*" | join clientip [search index=web method=GET uri_path="*/images/*.php" OR uri_path="*/media/*.php"].
      • File integrity (auditd/FIM): Watch the webroot with -w /var/www/html -p wa -k joomla_write and alert when php-fpm or apache2 writes PHP-extension files. Wazuh/OSSEC FIM on the upload directories works as an alternative.
      • Process ancestry (EDR/Sysmon for Linux EID 1): Web server processes such as php-fpm, apache2, httpd or nginx should not spawn shells or network tools. Sigma shape: ParentImage|endswith: ['/php-fpm','/apache2','/httpd'] AND Image|endswith: ['/sh','/bash','/curl','/wget','/nc','/python3','/perl']. On Windows/IIS, watch for w3wp.exe → cmd.exe/powershell.exe.
      • Network telemetry (Zeek/Suricata): Flag new outbound connections from the web server to unknown IPs, reverse-shell patterns (long-lived TCP sessions on unusual ports), and HTTP downloads of scripts or ELF binaries from the web segment.
      • Web shell content: Run YARA or grep across newly created files for patterns such as eval(base64_decode, assert($_, and $_REQUEST[ combined with system(, as well as heavily obfuscated PHP.

    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

    Joomla Extension - balbooa.com - Unauthenticated file upload in Balbooa Forms extension < 2.4.1 - The Joomla extension Balbooa Forms is vulnerable to an unauthenticated arbitrary file upload that allows uploading executable files and leads to full RCE.

    Source: NVD (NIST), CISA KEV Catalog, cvelistv5, 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
    balbooa.combalbooa.com Balbooa Forms extension for Joomla
    • 1.0-2.4.0
    • —
    balbooaforms
    • < 2.4.1
    • 2.4.1

    Vendors and products

    Weakness classes (CWE)

    • CWE-434Unrestricted Upload of File with Dangerous Type

      Base

      The product allows the upload or transfer of dangerous file types that are automatically processed within its environment.

      Entry at MITRE CWE-434

    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-2026-56291_PoC (opens in a new tab)github.comPoC (publicly reported)reported, not verified
    PoC-in-GitHub (nomi-sec)CVE-2026-56291 (opens in a new tab)github.comPoC (publicly reported)reported, not verified
    PoC-in-GitHub (nomi-sec)CVE-2026-56291.yaml (opens in a new tab)github.comPoC (publicly reported)reported, not verified
    PoC-in-GitHub (nomi-sec)CVE-2026-56291 (opens in a new tab)github.comPoC (publicly reported)reported, not verified

    References & sources

    • balbooa.comjoomla-formsProduct, Product
    • mysites.gurublog/balbooa-forms-unauthenticated-file-upload-flawThird-party advisory, Exploit, Third-party advisory
    • cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2026-56291government-resource, US government 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. NVD analysis modifiedNVD

    2. Record modifiedJoomla

      Description added or changed

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionchanged
      The Joomla extension Balbooa Forms is vulnerable to an unauthenticated arbitrary file upload that allows uploading executable files and leads to full RCE.
      Joomla Extension - balbooa.com - Unauthenticated file upload in Balbooa Forms extension < 2.4.1 - The Joomla extension Balbooa Forms is vulnerable to an unauthenticated arbitrary file upload that allows uploading executable files and leads to full RCE.

      Source identifier: security@joomla.org

    3. ReceivedJoomla

      CVSS V4.0: AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:A/AU:Y/U:Red

      Weakness type: CWE-434

      Description added or changed

      Show 6 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      balbooa.com Balbooa Forms extension for Joomla
      Descriptionadded
      —
      The Joomla extension Balbooa Forms is vulnerable to an unauthenticated arbitrary file upload that allows uploading executable files and leads to full RCE.
      CVSSadded
      —
      AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:A/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:Y/R:X/V:X/RE:X/U:Red
      Weakness type (CWE)added
      —
      CWE-434
      Referenceadded
      —
      https://mysites.guru/blog/balbooa-forms-unauthenticated-file-upload-flaw/
      Referenceadded
      —
      https://www.balbooa.com/joomla-forms

      Source identifier: security@joomla.org

    One NVD translation into another language is hidden.

    Linked advisories

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