wicked OOB Read in DHCPv4 Packet Capture (0.6.80)
CVE-2026-71402 Published on August 27, 2026
wicked: out-of-bounds read in the DHCPv4 option parser due to payload length taken from the IP total length
An out-of-bounds read was found in the DHCPv4 packet capture code of wicked. ni_capture_inspect_udp_header() in src/capture.c reports the IP total length as the payload length instead of the length of the remaining UDP payload. Consequently, the DHCP option walker in the DHCPv4 client (wickedd-dhcp4) reads up to ihl + 8 bytes at most 68 bytes past the end of the 1500-byte packet receive buffer. An unauthenticated attacker on the same network who sends a crafted DHCP/UDP packet can make the client parse adjacent heap memory as DHCP options, so that heap contents such as allocator metadata or pointer values can be interpreted into lease fields. The over-read is bounded to 68 bytes; no memory write, no attacker control over the adjacent bytes and no remote exfiltration primitive has been demonstrated. This issue affects wicked up to and including version 0.6.80.
Vulnerability Analysis
Weakness Types
Out-of-bounds Read
The software reads data past the end, or before the beginning, of the intended buffer. Typically, this can allow attackers to read sensitive information from other memory locations or cause a crash. A crash can occur when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string. The expected sentinel might not be located in the out-of-bounds memory, causing excessive data to be read, leading to a segmentation fault or a buffer overflow. The software may modify an index or perform pointer arithmetic that references a memory location that is outside of the boundaries of the buffer. A subsequent read operation then produces undefined or unexpected results.
What is a length manipulation Vulnerability?
The software parses a formatted message or structure, but it does not handle or incorrectly handles a length field that is inconsistent with the actual length of the associated data. If an attacker can manipulate the length parameter associated with an input such that it is inconsistent with the actual length of the input, this can be leveraged to cause the target application to behave in unexpected, and possibly, malicious ways. One of the possible motives for doing so is to pass in arbitrarily large input to the application. Another possible motivation is the modification of application state by including invalid data for subsequent properties of the application. Such weaknesses commonly lead to attacks such as buffer overflows and execution of arbitrary code.
CVE-2026-71402 has been classified to as a length manipulation vulnerability or weakness.
Affected Versions
SUSE wicked:- Before and including 0.6.80 is affected.