Threats Tagged 'cve-2026-18238'

A security update addresses an out-of-bounds read and write vulnerability in the libpcap library, which is used for low-level network monitoring. This vulnerability (CVE-2026-0799) allows arbitrary memory access. The issue affects multiple Red Hat Enterprise Linux 10 and related CodeReady Linux Builder products across various architectures. Red Hat has released an important security advisory with updated libpcap packages to fix this vulnerability.

Multiple vulnerabilities have been identified in libpcap, including out-of-bounds memory access, division by zero, infinite loops, improper header validation, memory leaks, and process termination due to invalid instructions. These issues affect the BPF interpreter and rpcap components, potentially leading to crashes, resource exhaustion, or memory corruption.

This is the official web site of tcpdump, a powerful command-line packet analyzer; and libpcap, a portable C/C++ library for network traffic capture. Security Fix(es): In BPF instructions that load/store a value from/to a scratch memory register the register index is an unsigned 32-bit integer and must not exceed 15, but libpcap BPF interpreter does not validate the value. In particular uncommon use cases a crafted filter program can cause the interpreter to try reading and writing the OS process memory in the 16GiB starting at the current stack frame on 64-bit architectures and in the entire address space on 32-bit architectures.(CVE-2026-0799) The rpcap client code that processes a RPCAP_MSG_PACKET message received from the server incorrectly validates its headers. A malicious server can send a crafted message and cause the client to treat up to 20 bytes of the client process memory beyond the end of the buffer as if it was a part of the captured packet.(CVE-2026-18238) rpcapd can allocate up to 65536 bytes per each RPCAP_MSG_UPDATEFILTER_REQ or RPCAP_MSG_STARTCAP_REQ message received from the client, but it never frees the memory, so it leaks memory even under normal use. A malicious client can cause the server to leak memory substantially faster.(CVE-2026-18313) libpcap BPF interpreter calls abort() if it encounters a BPF instruction that has an invalid opcode. In particular uncommon use cases a crafted filter program can terminate the OS process.(CVE-2026-31911) libpcap BPF interpreter detects neither reaching the end of the filter program buffer due to lack of a return instruction nor executing a jump instruction with an offset that translates to a pointer outside of the buffer. In particular uncommon use cases a crafted filter program can cause the interpreter to try reading the OS process memory in the 32GiB around the buffer on 64-bit architectures and in the entire address space on 32-bit architectures.(CVE-2026-31912) libpcap BPF interpreter for the 'div #k' and 'mod #k' ALU instructions does not check whether the immediate value is zero. In particular uncommon use cases a crafted filter program can cause a division by zero.(CVE-2026-6244) libpcap BPF interpreter treats the offset in the 'ja L' BPF instruction as a signed integer to implement looping via backward jumps, but it does not limit the number of loop iterations. In particular uncommon use cases a crafted filter program can cause the interpreter to loop infinitely.(CVE-2026-6554)

CVE-2026-18238 is a medium severity vulnerability in the libpcap library used by The Tcpdump Group. The rpcap client code improperly validates headers in RPCAP_MSG_PACKET messages from the server. This flaw allows a malicious server to cause the client to treat up to 20 bytes of memory beyond the buffer as part of the captured packet, potentially exposing sensitive memory contents.