Red Hat EUVD-2026-21734

libexif is a C library for parsing and manipulating EXIF metadata embedded in JPEG images. MakerNote fields are manufacturer-specific extensions that may contain proprietary camera settings and thumbnails. The integer underflow (CWE-191) occurs in size-validation logic when processing Fuji and Olympus MakerNote records-a signed or unsigned integer wraps around due to insufficient bounds checking, permitting out-of-bounds heap reads or writes. Affected versions include all libexif releases through 0.6.25; the vulnerability resides in the MakerNote parser module that handles variable-length binary data without robust overflow protection.