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CVE-2026-33636— LIBPNG has ARM NEON Palette Expansion Out-of-Bounds Read on AArch64

Quick assessment

Affected
pnggroup libpng
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

libpng是The PNG Development Group开源的一个可对PNG图形文件实现创建、读写等操作的PNG参考库。 LIBPNG 1.6.36至1.6.55版本存在缓冲区错误漏洞，该漏洞源于ARM/AArch64 Neon优化调色板扩展路径存在越界读取和写入。

CVSS 7.6 · High EPSS 0.75% · P55
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I. Basic Information for CVE-2026-33636

Vulnerability Information
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Vulnerability Title
LIBPNG has ARM NEON Palette Expansion Out-of-Bounds Read on AArch64
Source: CVE Program / CVE List V5
Vulnerability Description
LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files. In versions 1.6.36 through 1.6.55, an out-of-bounds read and write exists in libpng's ARM/AArch64 Neon-optimized palette expansion path. When expanding 8-bit paletted rows to RGB or RGBA, the Neon loop processes a final partial chunk without verifying that enough input pixels remain. Because the implementation works backward from the end of the row, the final iteration dereferences pointers before the start of the row buffer (OOB read) and writes expanded pixel data to the same underflowed positions (OOB write). This is reachable via normal decoding of attacker-controlled PNG input if Neon is enabled. Version 1.6.56 fixes the issue.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
跨界内存读
Source: CVE Program / CVE List V5
Vulnerability Title
libpng 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
libpng是The PNG Development Group开源的一个可对PNG图形文件实现创建、读写等操作的PNG参考库。 LIBPNG 1.6.36至1.6.55版本存在缓冲区错误漏洞，该漏洞源于ARM/AArch64 Neon优化调色板扩展路径存在越界读取和写入。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
pnggroup libpng >= 1.6.36, < 1.6.56 -

II. Public POCs for CVE-2026-33636

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III. Intelligence Information for CVE-2026-33636

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Patches & Fixes for CVE-2026-33636 (2)

Vendor Advisories for CVE-2026-33636 (1)

IV. Related Vulnerabilities

Same product: libpng
Same vendor: pnggroup
Same weakness: CWE-125