An integer underflow vulnerability exists in the `nextstate()` function in `gpsd/packet.c` of gpsd versions prior to commit `ffa1d6f40bca0b035fc7f5e563160ebb67199da7`. When parsing a NAVCOM packet, the payload length is calculated using `lexer->length = (size_t)c - 4` without checking if the input byte `c` is less than 4. This results in an unsigned integer underflow, setting `lexer->length` to a very large value (near `SIZE_MAX`). The parser then enters a loop attempting to consume this massive number of bytes, causing 100% CPU utilization and a Denial of Service (DoS) condition.

gpsd before commit dc966aa contains a heap-based out-of-bounds write vulnerability in the drivers/driver_nmea2000.c file. The hnd_129540 function, which handles NMEA2000 PGN 129540 (GNSS Satellites in View) packets, fails to validate the user-supplied satellite count against the size of the skyview array (184 elements). This allows an attacker to write beyond the bounds of the array by providing a satellite count up to 255, leading to memory corruption, Denial of Service (DoS), and potentially arbitrary code execution.

An integer underflow vulnerability exists in the NTRIP Stream Parsing functionality of GPSd 3.25.1~dev. A specially crafted network packet can lead to memory corruption. An attacker can send a malicious packet to trigger this vulnerability.

gpsd versions 2.90 to 3.17 and microjson versions 1.0 to 1.3, an open source project, allow a stack-based buffer overflow, which may allow remote attackers to execute arbitrary code on embedded platforms via traffic on Port 2947/TCP or crafted JSON inputs.

The NMEA0183 driver in gpsd before 3.9 allows remote attackers to cause a denial of service (daemon termination) and possibly execute arbitrary code via a GPS packet with a malformed $GPGGA interpreted sentence that lacks certain fields and a terminator. NOTE: a separate issue in the AIS driver was also reported, but it might not be a vulnerability.