CVE-2026-33416
LIBPNG has use-after-free via pointer aliasing in `png_set_tRNS` and `png_set_PLTE`
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.
INFO
Published Date :
March 26, 2026, 5:16 p.m.
Last Modified :
April 2, 2026, 8:28 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update Libpng library to version 1.6.56.
- Review code for manual memory management of PNG data.
- Ensure proper buffer handling in image processing functions.
Public PoC/Exploit Available at Github
CVE-2026-33416 has a 2 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-33416.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-33416 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-33416
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
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Java
DSA and DLA for Debian last 14 days
Python
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-33416 vulnerability anywhere in the article.
-
CybersecurityNews
PNG Vulnerabilities Allow Attackers to Trigger Process Crashes, Leak Sensitive Information
Two high-severity vulnerabilities have been discovered in libpng, the widely used reference library for reading and writing PNG images. These flaws allow attackers to trigger process crashes, leak sen ... Read more
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Daily CyberSecurity
The 30-Year Glitch: RCE and ARM Exploits Uncovered in libpng Reference Library
Security researchers have disclosed two significant vulnerabilities in libpng, the official reference library for Portable Network Graphics (PNG). The flaws, which impact versions spanning decades of ... Read more
The following table lists the changes that have been made to the
CVE-2026-33416 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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Initial Analysis by [email protected]
Apr. 02, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:libpng:libpng:*:*:*:*:*:*:*:* versions from (including) 1.2.1 up to (excluding) 1.6.56 Added Reference Type GitHub, Inc.: https://github.com/pnggroup/libpng/commit/23019269764e35ed8458e517f1897bd3c54820eb Types: Patch Added Reference Type GitHub, Inc.: https://github.com/pnggroup/libpng/commit/7ea9eea884a2328cc7fdcb3c0c00246a50d90667 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/pnggroup/libpng/commit/a3a21443ed12bfa1ef46fa0d4fb2b74a0fa34a25 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/pnggroup/libpng/commit/c1b0318b393c90679e6fa5bc1d329fd5d5012ec1 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/pnggroup/libpng/pull/824 Types: Exploit, Issue Tracking Added Reference Type GitHub, Inc.: https://github.com/pnggroup/libpng/security/advisories/GHSA-m4pc-p4q3-4c7j Types: Patch, Vendor Advisory -
New CVE Received by [email protected]
Mar. 26, 2026
Action Type Old Value New Value Added 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. Added CVSS V3.1 AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H Added CWE CWE-416 Added Reference https://github.com/pnggroup/libpng/commit/23019269764e35ed8458e517f1897bd3c54820eb Added Reference https://github.com/pnggroup/libpng/commit/7ea9eea884a2328cc7fdcb3c0c00246a50d90667 Added Reference https://github.com/pnggroup/libpng/commit/a3a21443ed12bfa1ef46fa0d4fb2b74a0fa34a25 Added Reference https://github.com/pnggroup/libpng/commit/c1b0318b393c90679e6fa5bc1d329fd5d5012ec1 Added Reference https://github.com/pnggroup/libpng/pull/824 Added Reference https://github.com/pnggroup/libpng/security/advisories/GHSA-m4pc-p4q3-4c7j