CVE-2020-27738 Memory corruption in APOGEE PXC Compact (BACnet)
An attacker can cause a denial-of-service condition in Siemens building automation systems by sending malformed DNS responses that trigger an out-of-bounds read.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2020-27738?
CVE-2020-27738 is a medium-severity memory corruption vulnerability in Siemens APOGEE PXC Compact (BACnet), published on 22 Apr 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A vulnerability has been identified in APOGEE PXC Compact (BACnet) (All versions < V3.5.5), APOGEE PXC Compact (P2 Ethernet) (All versions < V2.8.20), APOGEE PXC Modular (BACnet) (All versions < V3.5.5), APOGEE PXC Modular (P2 Ethernet) (All versions < V2.8.20), Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions < V2017.02.3), Nucleus ReadyStart V4 (All versions < V4.1.0), Nucleus Source Code (Versions including affected DNS modules), SIMOTICS CONNECT 400 (All versions < V0.5.0.0), TALON TC Compact (BACnet) (All versions < V3.5.5), TALON TC Modular (BACnet) (All versions < V3.5.5). The DNS domain name record decompression functionality does not properly validate the pointer offset values. The parsing of malformed responses could result in a read access past the end of an allocated structure. An attacker with a privileged position in the network could leverage this vulnerability to cause a denial-of-service condition.
Which versions are affected by CVE-2020-27738?
It affects 5 products.
Products include Siemens Nucleus Net, Siemens Nucleus Readystart V3, Siemens Nucleus Readystart V4, Siemens Nucleus Source Code, Siemens Simotics Connect 400 Firmware.
How do I fix CVE-2020-27738?
No fix has been published for CVE-2020-27738 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2020-27738 being exploited?
There is no known exploitation of CVE-2020-27738 in the wild and no public exploit code.
Other vulnerabilities in Siemens APOGEE PXC Compact (BACnet)
- CVE-2020-15795 Memory corruption in APOGEE PXC Compact (BACnet)
- CVE-2020-27009 Memory corruption in APOGEE PXC Compact (BACnet)
- CVE-2020-27736 Memory corruption in APOGEE PXC Compact (BACnet)
- CVE-2020-27737 Memory corruption in APOGEE PXC Compact (BACnet)
- CVE-2021-25677 Other in APOGEE PXC Compact (BACnet)
Sources
Also known as GHSA-pqww-3mgv-r6mj.