{"id":"DEBIAN-CVE-2026-33416","details":"LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files. In versions 1.2.1 through 1.6.55, `png_set_tRNS` and `png_set_PLTE` each alias a heap-allocated buffer between `png_struct` and `png_info`, sharing a single allocation across two structs with independent lifetimes. The `trans_alpha` aliasing has been present since at least libpng 1.0, and the `palette` aliasing since at least 1.2.1. Both affect all prior release lines `png_set_tRNS` sets `png_ptr-\u003etrans_alpha = info_ptr-\u003etrans_alpha` (256-byte buffer) and `png_set_PLTE` sets `info_ptr-\u003epalette = png_ptr-\u003epalette` (768-byte buffer). In both cases, calling `png_free_data` (with `PNG_FREE_TRNS` or `PNG_FREE_PLTE`) frees the buffer through `info_ptr` while the corresponding `png_ptr` pointer remains dangling. Subsequent row-transform functions dereference and, in some code paths, write to the freed memory. A second call to `png_set_tRNS` or `png_set_PLTE` has the same effect, because both functions call `png_free_data` internally before reallocating the `info_ptr` buffer. Version 1.6.56 fixes the issue.","modified":"2026-09-01T16:06:39.566919224Z","published":"2026-03-26T17:16:38.443Z","upstream":["CVE-2026-33416"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-33416"}],"affected":[{"package":{"name":"libpng1.6","ecosystem":"Debian:12","purl":"pkg:deb/debian/libpng1.6?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.6.39-2+deb12u4"}]}],"versions":["1.6.39-2","1.6.39-2+deb12u1","1.6.39-2+deb12u2","1.6.39-2+deb12u3"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33416.json"}},{"package":{"name":"libpng1.6","ecosystem":"Debian:13","purl":"pkg:deb/debian/libpng1.6?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.6.48-1+deb13u4"}]}],"versions":["1.6.48-1","1.6.48-1+deb13u1","1.6.48-1+deb13u2","1.6.48-1+deb13u3"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33416.json"}},{"package":{"name":"libpng1.6","ecosystem":"Debian:14","purl":"pkg:deb/debian/libpng1.6?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.6.56-1"}]}],"versions":["1.6.48-1","1.6.49-1~exp1","1.6.50-1","1.6.50-1~exp1","1.6.51-1","1.6.52-1","1.6.53-1","1.6.54-1","1.6.55-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33416.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H"}]}