LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files. From 1.0.9 to before 1.6.57, passing a pointer obtained from png_get_PLTE, png_get_tRNS, or png_get_hIST back into the corresponding setter on the same png_struct/png_info pair causes the setter to read from freed memory and copy its contents into the replacement buffer. The setter frees the internal buffer before copying from the caller-supplied pointer, which now dangles.
The freed region may contain stale data (producing silently corrupted chunk metadata) or data from subsequent heap allocations (leaking unrelated heap contents into the chunk struct). This vulnerability is fixed in 1.6.57.
Attack Parameters
Attack Vector
Local
Requires local access
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
Low
Partial data leak
Integrity
Low
Partial data modification
Availability
None
No disruption
CVSS Vector v3.1
Weakness Type (CWE)
References 5
https://github.com/pnggroup/libpng/commit/398cbe3df03f4e11bb031e07f416dfdde3684…
security-advisories@github.com
https://github.com/pnggroup/libpng/commit/55d20aaa322c9274491cda82c5cd4f99b48c6…
security-advisories@github.com
https://github.com/pnggroup/libpng/issues/836
security-advisories@github.com
https://github.com/pnggroup/libpng/issues/837
security-advisories@github.com
https://github.com/pnggroup/libpng/security/advisories/GHSA-6fr7-g8h7-v645
security-advisories@github.com