CVE-2020-25643
📋 TL;DR
This vulnerability in the Linux kernel's HDLC_PPP module allows memory corruption and read overflow due to improper input validation in the ppp_cp_parse_cr function. It can lead to system crashes, denial of service, and potential data confidentiality/integrity compromise. Affects Linux systems with kernel versions before 5.9-rc7 that use HDLC/PPP networking.
💻 Affected Systems
- Linux kernel
📦 What is this software?
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Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Starwind Virtual San by Starwindsoftware
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Starwind Virtual San by Starwindsoftware
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⚠️ Risk & Real-World Impact
Worst Case
Complete system crash leading to prolonged denial of service, potential kernel memory corruption enabling privilege escalation or data leakage
Likely Case
System crash or kernel panic causing temporary denial of service, requiring system reboot
If Mitigated
Minimal impact if HDLC/PPP is not used or systems are properly segmented
🎯 Exploit Status
Exploitation requires sending specially crafted packets to HDLC/PPP interfaces. No public exploit code identified.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Linux kernel 5.9-rc7 and later
Vendor Advisory: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=66d42ed8b25b64eb63111a2b8582c5afc8bf1105
Restart Required: Yes
Instructions:
1. Update kernel to version 5.9-rc7 or later. 2. For distributions: Apply vendor patches. 3. Reboot system to load new kernel.
🔧 Temporary Workarounds
Disable HDLC/PPP module
linuxPrevent loading of vulnerable kernel module
echo 'install hdlc /bin/false' >> /etc/modprobe.d/disable-hdlc.conf
echo 'install ppp /bin/false' >> /etc/modprobe.d/disable-ppp.conf
rmmod hdlc ppp
Block HDLC/PPP network traffic
linuxPrevent exploitation via network filtering
iptables -A INPUT -p 0x00FF -j DROP
iptables -A FORWARD -p 0x00FF -j DROP
🧯 If You Can't Patch
- Disable HDLC/PPP interfaces if not required
- Implement network segmentation to isolate HDLC/PPP traffic
🔍 How to Verify
Check if Vulnerable:
Check kernel version: uname -r. If version is earlier than 5.9-rc7 and HDLC/PPP is loaded, system is vulnerable.Check Version:
uname -rVerify Fix Applied:
Verify kernel version is 5.9-rc7 or later: uname -r. Check that HDLC/PPP modules are not loaded: lsmod | grep -E 'hdlc|ppp'📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages
- System crash/reboot logs
- HDLC/PPP error messages in dmesg
Network Indicators:
- Unusual HDLC/PPP protocol traffic
- Malformed packet patterns on HDLC interfaces
SIEM Query:
source="kernel" AND ("panic" OR "Oops" OR "hdlc" OR "ppp")🔗 References
- http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00021.html
- http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00042.html
- https://bugzilla.redhat.com/show_bug.cgi?id=1879981
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=66d42ed8b25b64eb63111a2b8582c5afc8bf1105
- https://lists.debian.org/debian-lts-announce/2020/10/msg00028.html
- https://lists.debian.org/debian-lts-announce/2020/10/msg00032.html
- https://lists.debian.org/debian-lts-announce/2020/10/msg00034.html
- https://security.netapp.com/advisory/ntap-20201103-0002/
- https://www.debian.org/security/2020/dsa-4774
- https://www.starwindsoftware.com/security/sw-20210325-0002/
- http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00021.html
- http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00042.html
- https://bugzilla.redhat.com/show_bug.cgi?id=1879981
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=66d42ed8b25b64eb63111a2b8582c5afc8bf1105
- https://lists.debian.org/debian-lts-announce/2020/10/msg00028.html
- https://lists.debian.org/debian-lts-announce/2020/10/msg00032.html
- https://lists.debian.org/debian-lts-announce/2020/10/msg00034.html
- https://security.netapp.com/advisory/ntap-20201103-0002/
- https://www.debian.org/security/2020/dsa-4774
- https://www.starwindsoftware.com/security/sw-20210325-0002/
