CVE-2026-55738 describes a stack-based buffer overflow in the raw_to_header() function of rxi microtar 0.1.0. The vulnerability arises from the use of strcpy() to copy the 100-byte name and linkname fields of a TAR header without guaranteeing null termination. Since the POSIX ustar format allows these fields to be fully populated with non-null bytes, a crafted TAR archive with a non-null-terminated linkname field can cause strcpy() to read beyond the 512-byte raw header buffer on the stack and write past the destination buffer. This leads to a stack buffer overflow, confirmed by AddressSanitizer, which can result in denial of service or arbitrary code execution when the archive is opened or parsed via mtar_open(), mtar_read_header(), or mtar_find().

Successful exploitation allows a remote attacker to cause a denial of service (application crash) or potentially execute arbitrary code on the victim system by supplying a malicious TAR archive that triggers the stack buffer overflow during parsing.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, avoid opening or parsing untrusted TAR archives with rxi microtar 0.1.0 to mitigate risk.