Discovery API Icon
Discovery API
Security Advisory Icon
Security Advisory
Package Manager Icon
Package Manager
Alpaquita LinuxStreamSecurity Advisory
Search Cve

CVE-2026-33416

Published: March 27, 2026Last modified: March 28, 2026

Description

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->trans_alpha = info_ptr->trans_alpha` (256-byte buffer) and `png_set_PLTE` sets `info_ptr->palette = png_ptr->palette` (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.

Severity score breakdown

ParameterValue
Base score7.5
Attack VectorNETWORK
Attack complexityHIGH
Privileges requiredNONE
User interactionREQUIRED
ScopeUNCHANGED
ConfidentialityHIGH
Integrity impactHIGH
Availability impactHIGH
VectorCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

Status

ProductReleasePackageStatus
Alpaquita Linux23 LTSlibpngFixed (1.6.56-r0)
25 LTSlibpngFixed (1.6.56-r0)
StreamlibpngFixed (1.6.56-r0)
Hardened Containers23 LTSlibpngFixed (1.6.56-r0)
25 LTSlibpngFixed (1.6.56-r0)
StreamlibpngFixed (1.6.56-r0)

References

ON THIS PAGE