CriticalCVE-2022-36537

    ZK Framework AuUploader Unspecified Vulnerability (CVE-2022-36537)

    Published In CISA KEV since Sources: SingCERT, pwn.watch, CVE.org, OSV

    What is affected, what to do

    ZK Framework v9.6.1, 9.6.0.1, 9.5.1.3, 9.0.1.2 and 8.6.4.1 allows attackers to access sensitive information via a crafted POST request sent to the component AuUploader.

    The vulnerability is being actively exploited; treat it as a priority. CISA lists it as used in ransomware campaigns. Update ZK Framework AuUploader to version 8.6.4.2, ZK Framework AuUploader to version 9.0.1.3, ZK Framework AuUploader to version 9.5.1.3. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • ZK Framework AuUploader lt *..8.6.4.2
    • ZK Framework AuUploader lt 9.0.0..9.0.1.3
    • ZK Framework AuUploader lt 9.5.0..9.5.1.3
    • ZK Framework AuUploader lt 9.6.0..9.6.2
    Fixed in
    • ZK Framework AuUploader 8.6.4.2
    • ZK Framework AuUploader 9.0.1.3
    • ZK Framework AuUploader 9.5.1.3
    • ZK Framework AuUploader 9.6.2

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

    Metrics

    7.5

    Priority

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

    Source: NVD, CVSS v3

    7.5

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: SingCERT, pwn.watch, CVE.org, OSV

    95.4 %

    EPSS score

    High — model estimates ≥ 50% chance of real-world exploitation within 30 days.

    Source: FIRST EPSS, percentile 99.87

    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
    243.60 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 exploited
    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
    7.5 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
    7.5
    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
    95.4 %
    High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
    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
    99.87
    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
    CISA assessment (SSVC)
    Exploitation: active · automatable · Technical impact: partial
    Source: CISA Vulnrichment, as of 29 January 2025

    Response and mitigation

    Why act now?

    Prioritisation rationale

    This CVE is on KEV with a confirmed ransomware-campaign flag — the Clop/TA505 cluster weaponised it against R1Soft backup servers in late 2022 and early 2023. Backup servers are the highest-value initial foothold because compromise enables both lateral movement and destruction of recovery options. The CVSS vector is network-reachable, unauthenticated and requires no user interaction, and the exploitation likelihood ranks among the very highest in the entire KEV catalogue. For NIS2-regulated organisations running R1Soft, the ConnectWise stack or in-house ZK-based Java applications, treat this as P1: patch or take offline within 24 hours and run a compromise assessment in parallel, even on apparently quiet hosts, because public PoCs have been circulating for more than two years.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Upgrade ZK Framework to a fixed release: 9.6.2, 9.5.1.3, 9.0.1.3 or 8.6.4.2. For Maven builds, bump org.zkoss.zk:zk plus transitive artefacts (zul, zkbind, zkplus) to the matching patch line and redeploy.
      • Enumerate every product that embeds ZK — notably ConnectWise R1Soft Server Backup Manager (upgrade to SBM 6.16.3 or later), plus any in-house Java webapp. Grep WEB-INF/lib for zk-*.jar, zul-*.jar, zcommon-*.jar and read the version from META-INF/MANIFEST.MF.
      • Pull R1Soft and ZK admin consoles off the public internet until patched — restrict perimeter firewall rules for the relevant ports (R1Soft commonly 8080/8443/1167) to the management VLAN only.
      • Compromise triage on exposed hosts: inspect /opt/r1soft, webapp roots and tmp directories for rogue JSP webshells, new cron entries, fresh SSH keys in ~root/.ssh/authorized_keys and persistence from TrueBot or FlawedGrace. Isolate suspicious hosts rather than only patching them.
      • Rotate every credential stored on the backup server (DB accounts, hypervisor API tokens, agent shared secrets); the AuUploader path can exfiltrate configuration files from the web context.

    2. Runbook step 2

      Mitigation layers

      • Network segmentation: place backup infrastructure and ZK admin interfaces into a dedicated management VLAN reachable only through an MFA-protected jump host. Apply egress filtering so backup servers can only reach defined agent IPs and update endpoints.
      • Reverse proxy / WAF rule: block or restrict to internal authenticated clients any POST request to URIs containing AuUploader, zkau, /zkau/upload. Add a content-type filter that rejects multipart uploads containing ../ or absolute paths in the nextURI parameter.
      • Application-server hardening: configure Tomcat/Jetty policy so the servlet container cannot read configuration directories (WEB-INF/, conf/) outside its intended scope; enable the SecurityManager where legacy code tolerates it.
      • Least privilege for the service account: run the ZK or R1Soft process as a dedicated unprivileged user with read-only access to backup volumes, never as root/SYSTEM.
      • IPS signature coverage (Suricata/Snort): enable the ET and ETPRO SIDs for CVE-2022-36537 (search ruleset for ZK Framework AuUploader), force a ruleset update and switch alert-to-block on perimeter sensors in front of backup infrastructure.
      • Post-patch vulnerability scan: run Qualys QID 378785, Tenable plugin 171038 or equivalent to catch vulnerable instances hiding in shadow IT.

    3. Runbook step 3

      Detection rules

      • Web access logs: POST to URIs containing /zkau or parameter AuUploader combined with nextURI= and traversal patterns (..%2f, ..\\, WEB-INF). SPL sketch: index=web sourcetype=access_combined method=POST uri_path="*zkau*" uri_query="*nextURI*" OR uri_query="*WEB-INF*".
      • Response-size anomaly: 200 responses to /zkau POSTs with content-length far above the baseline median — a strong hint of exfiltrated configuration files.
      • Sysmon EID 1 / auditd execve: unexpected child processes under the Java process of the ZK or R1Soft host, especially sh, bash, cmd.exe, powershell.exe, wget, curl, certutil. Sigma shape: parent_image endswith java.exe AND child_image in (shell list).
      • EDR file-create events: new .jsp, .jspx or .class files appearing in R1Soft webapp paths (/usr/sbin/r1soft/web/) or ZK deployment directories outside planned deployment windows.
      • Network telemetry (Zeek): outbound connections from the backup server to non-whitelisted IPs or ASNs, especially TLS to newly registered domains — indicative of TrueBot or Cobalt Strike beaconing after initial access.

    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

    ZK Framework v9.6.1, 9.6.0.1, 9.5.1.3, 9.0.1.2 and 8.6.4.1 allows attackers to access sensitive information via a crafted POST request sent to the component AuUploader.

    Source: CSA/SingCERT, pwn.watch, NVD (NIST), OSV (Open Source Vulnerabilities), cvelistv5, CISA KEV Catalog, 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
    zkosszk_framework
    • 9.5.0 – < 9.5.1.3
    • 9.0.0 – < 9.0.1.3
    • 9.6.0 – < 9.6.2
    • < 8.6.4.2
    • 9.5.1.3
    • 9.0.1.3
    • 9.6.2
    • 8.6.4.2
    mavenorg.zkoss.zk:zk
    • 3.6.0
    • 9.6.0.1-jakarta
    • 3.0.0
    • 9.6.0-jakarta
    • 2.4.2
    • 3.0.6
    • 6.0.0
    • 8.0.0-RC
    • 3.6.2
    • 7.0.2
    • 3.0.0-RC
    • 3.0.4
    • 9.5.0.0
    • 3.6.2-FL-20090515
    • 2.3.1
    • 6.5.3
    • 3.0.7
    • 2.1.3
    • 3.0.8
    • 3.0.3
    • 7.0.0-Preview
    • 9.5.0.1
    • 3.6.2.FL.20090518
    • 3.5.1
    • 9.0.0.0
    • 2.4.1
    • 9.6.0
    • 6.0.2
    • 3.0.5
    • 2.3.0
    • 9.0.0
    • 9.5.0
    • 6.5.1.1
    • 9.6.1
    • 5.0.10
    • 9.5.0.2
    • 3.5.2
    • 5.0.8
    • 7.0.0
    • 7.0.3
    • 6.5.4
    • 9.5.0.3
    • 9.0.0.1
    • 5.0.0.RC
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    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

    References & sources

    • NVD (NIST)NVD: CVE-2022-36537advisory, pwn-watch
    • github.comzkoss/zk/commit/92a29aa9b1daf1fd2d9d188cb6545f0441d54e84web
    • github.comzkoss/zkpackage
    • tracker.zkoss.orgVendor advisory: ZK Framework AuUploaderweb, Issue tracking, Patch, Vendor advisory, pwn-watch
    • bleepingcomputer.comnews/security/cisa-warns-of-hackers-exploiting-zk-java-framewor…web
    • cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2022-36537web, government-resource, US government resource
    • bleepingcomputer.comnews/security/cisa-warns-of-hackers-exploiting-zk-java-framewor…Third-party advisory
    • pwn.watchpwn.watch: ZK Framework AuUploader: Unspecified (CVE-2022-36537)pwn-watch
    • cisa.govCISA Known Exploited Vulnerabilities Catalogpwn-watch
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