← Vulnerability feed

Vulnerability record · CVE-2026-33416 · published 26 March 2026

CVE-2026-33416: Libpng use after free vulnerability

LLibpng · Libpng

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.

7.5 CVSS 3.1 High EPSS 0.52% · top 58.4% CWE-416 · Use after free
7.5CVSS 3.1 base score
0.52%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
6References, 1 tagged exploit
17 Jun 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/pnggroup/libpng/commit/23019269764e35ed8458e517f1897bd3c54820eb Patch
https://github.com/pnggroup/libpng/commit/7ea9eea884a2328cc7fdcb3c0c00246a50d90667 Patch
https://github.com/pnggroup/libpng/commit/a3a21443ed12bfa1ef46fa0d4fb2b74a0fa34a25 Patch
https://github.com/pnggroup/libpng/commit/c1b0318b393c90679e6fa5bc1d329fd5d5012ec1 Patch
https://github.com/pnggroup/libpng/pull/824 ExploitIssue Tracking
https://github.com/pnggroup/libpng/security/advisories/GHSA-m4pc-p4q3-4c7j PatchVendor Advisory

Track CVE-2026-33416 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2017-12652Libpng improper input validation vulnerabilitylibpng before 1.6.32 does not properly check the length of chunks against the user limit.EPSS 4.1%9.8CVE-2010-1205Libpng classic buffer overflow vulnerabilityBuffer overflow in pngpread.c in libpng before 1.2.44 and 1.4.x before 1.4.3, as used in progressive applications, might allow remote attackers to ex…EPSS 43%8.8CVE-2018-14550Libpng out-of-bounds write vulnerabilityAn issue has been found in third-party PNM decoding associated with libpng 1.6.35. It is a stack-based buffer overflow in the function get_token in p…EPSS 3.5%8.8CVE-2015-8540Redhat enterprise linux desktop supplementary vulnerabilityInteger underflow in the png_check_keyword function in pngwutil.c in libpng 0.90 through 0.99, 1.0.x before 1.0.66, 1.1.x and 1.2.x before 1.2.56, 1.…EPSS 6.5%8.8CVE-2015-0973Oracle solaris memory buffer overflow vulnerabilityBuffer overflow in the png_read_IDAT_data function in pngrutil.c in libpng before 1.5.21 and 1.6.x before 1.6.16 allows context-dependent attackers t…EPSS 4.1%8.8CVE-2014-9495Apple mac os x memory buffer overflow vulnerabilityHeap-based buffer overflow in the png_combine_row function in libpng before 1.5.21 and 1.6.x before 1.6.16, when running on 64-bit systems, might all…EPSS 4.1%8.8CVE-2011-3045Google chrome integer overflow vulnerabilityInteger signedness error in the png_inflate function in pngrutil.c in libpng before 1.4.10beta01, as used in Google Chrome before 17.0.963.83 and oth…EPSS 3.6%8.8CVE-2011-2690Libpng classic buffer overflow vulnerabilityBuffer overflow in libpng 1.0.x before 1.0.55, 1.2.x before 1.2.45, 1.4.x before 1.4.8, and 1.5.x before 1.5.4, when used by an application that call…EPSS 3.3%

Source: NIST National Vulnerability Database (record CVE-2026-33416), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.