PYSEC-2026-1354

Impact

An out-of-bounds read was found in Exiv2 versions v0.28.5 and earlier. Exiv2 is a command-line utility and C++ library for reading, writing, deleting, and modifying the metadata of image files. The out-of-bounds read is triggered when Exiv2 is used to write metadata into a crafted image file. An attacker could potentially exploit the vulnerability to cause a denial of service by crashing Exiv2, if they can trick the victim into running Exiv2 on a crafted image file.

Note that this bug is only triggered when writing the metadata, which is a less frequently used Exiv2 operation than reading the metadata. For example, to trigger the bug in the Exiv2 command-line application, you need to add an extra command-line argument such as delete.

Patches

The bug is fixed in version v0.28.6.

Credit

Thank you to @dragonArthurX for reporting this issue.

Details (from original report by @dragonArthurX )

Version: Tested on v0.28.5 (latest official release) Commit: 907169fa643c2c74c14fd4106e55eaeee3634d9f

Platform: Ubuntu 20.04.6 LTS (x86_64)

Build Steps:

git clone https://github.com/Exiv2/exiv2.git
cd exiv2
git checkout v0.28.5
mkdir build-v0.28.5 && cd build-v0.28.5
cmake -DCMAKE_C_COMPILER=/fuzzer/afl-clang-fast -DCMAKE_CXX_COMPILER=/fuzzer/afl-clang-fast++ -DCMAKE_C_FLAGS="-g -fsanitize=address" -DCMAKE_CXX_FLAGS="-g -fsanitize=address" -DBUILD_SHARED_LIBS=OFF ../

Command line to reproduce:

/home/exiv2/build/bin/exiv2 -d a -f /home/poc 

Crash Output:

AddressSanitizer:DEADLYSIGNAL
 ================================================================ = 
==376531==ERROR: AddressSanitizer: SEGV on unknown address 0x7fd92236b0e7 (pc 0x7fd82314dcd2 bp 0x7ffd540ceba0 sp 0x7ffd540ce358 T0)
==376531==The signal is caused by a READ memory access.
    #0 0x7fd82314dcd2  /build/glibc-B3wQXB/glibc-2.31/string/../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S:383
    #1 0x4ed131 in __asan_memcpy...