CVE-2020-13848
📋 TL;DR
CVE-2020-13848 is a NULL pointer dereference vulnerability in Portable UPnP SDK (libupnp) that allows remote attackers to cause denial of service (crash) via specially crafted SSDP messages. This affects any device or application using vulnerable versions of libupnp for UPnP functionality, including IoT devices, routers, media servers, and network applications.
💻 Affected Systems
- Portable UPnP SDK (libupnp)
- Any software using libupnp library
📦 What is this software?
Libupnp by Libupnp Project
⚠️ Risk & Real-World Impact
Worst Case
Remote unauthenticated attacker crashes the UPnP service, potentially disrupting network discovery, media streaming, or device communication services that depend on UPnP functionality.
Likely Case
Service disruption affecting UPnP-dependent applications, requiring service restart to recover functionality.
If Mitigated
Minimal impact if UPnP services are disabled or network access is restricted.
🎯 Exploit Status
Exploitation requires sending crafted SSDP packets to vulnerable UPnP service. Proof-of-concept code is available in public repositories.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.12.2 and later
Vendor Advisory: https://github.com/pupnp/pupnp/commit/c805c1de1141cb22f74c0d94dd5664bda37398e0
Restart Required: Yes
Instructions:
1. Update libupnp to version 1.12.2 or later. 2. Recompile applications using libupnp with updated library. 3. Restart affected services or applications.
🔧 Temporary Workarounds
Disable UPnP services
linuxDisable UPnP functionality if not required
systemctl stop upnpd
service upnp stop
Network filtering
linuxBlock SSDP traffic (UDP port 1900) at network perimeter
iptables -A INPUT -p udp --dport 1900 -j DROP
🧯 If You Can't Patch
- Implement network segmentation to isolate UPnP services from untrusted networks
- Deploy intrusion prevention systems to detect and block SSDP exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check libupnp version: dpkg -l | grep libupnp or rpm -qa | grep upnp. If version is 1.12.1 or earlier, system is vulnerable.Check Version:
pkg-config --modversion libupnpVerify Fix Applied:
Verify libupnp version is 1.12.2 or later and UPnP services are running without crashes after patch.📡 Detection & Monitoring
Log Indicators:
- UPnP service crashes
- Segmentation fault errors in system logs
- Service restart messages
Network Indicators:
- Unusual SSDP traffic patterns
- Multiple SSDP requests from single source
SIEM Query:
source="systemd" "segmentation fault" AND "upnp" OR source="kernel" "segfault" AND process="upnp"🔗 References
- http://lists.opensuse.org/opensuse-security-announce/2020-06/msg00030.html
- http://lists.opensuse.org/opensuse-security-announce/2020-06/msg00033.html
- https://github.com/pupnp/pupnp/commit/c805c1de1141cb22f74c0d94dd5664bda37398e0
- https://github.com/pupnp/pupnp/issues/177
- https://lists.debian.org/debian-lts-announce/2020/06/msg00006.html
- https://lists.debian.org/debian-lts-announce/2021/03/msg00007.html
- http://lists.opensuse.org/opensuse-security-announce/2020-06/msg00030.html
- http://lists.opensuse.org/opensuse-security-announce/2020-06/msg00033.html
- https://github.com/pupnp/pupnp/commit/c805c1de1141cb22f74c0d94dd5664bda37398e0
- https://github.com/pupnp/pupnp/issues/177
- https://lists.debian.org/debian-lts-announce/2020/06/msg00006.html
- https://lists.debian.org/debian-lts-announce/2021/03/msg00007.html
