Description
The PNG chunk reader has no notion of chunk ordering. It records whether an IDAT has been seen and whether a tRNS has already supplied transparency, but nothing prevents an IHDR being read a second time.



A PNG carries exactly one IHDR and it is the first chunk. A file that places a second one after IDAT rewrites the image width, height, bit depth and pixel depth *after* the decoded-data buffer has already been allocated and filled from the original values. The pass that reverses the PNG row filters then derives its own extent from the new dimensions and walks the old allocation, moving image bytes past the end of it.



The buffer is allocated by GUIX rather than supplied by the caller, so the application has no way to size it defensively. The decoder is compiled in by default.
Published: 2026-10-20
Score: 8.4 High
EPSS: n/a
KEV: No
Impact: Remote Code Execution
Action: Immediate Patch
AI Analysis

Impact

The PNG chunk reader incorrectly accepts a duplicate IHDR chunk after an IDAT, causing the decoder to recompute image dimensions and attempt to write beyond the originally allocated buffer. This heap out‑of‑bounds write can corrupt memory or lead to arbitrary code execution. The vulnerability is a classic example of a buffer overrun (CWE‑787) and an out‑of‑bounds write (CWE‑125). The affected code resides in Eclipse ThreadX's GUIX component, which does not provide defensive sizing during allocation and is compiled into applications by default.

Affected Systems

Eclipse ThreadX – GUIX from the Eclipse Foundation is the affected product. No specific version numbers are listed in the CVE data, so all releases using the default PNG decoder should be evaluated. The product may be present in various embedded or desktop applications that embed the GUIX library.

Risk and Exploitability

The CVSS score of 8.4 indicates a high severity. EPSS information is not available, and the vulnerability is not listed in CISA’s KEV catalog. The likely attack vector is local or remote execution of malicious PNG files supplied to any component that processes user‑generated images. Because the decoder is compiled in by default and the buffer is allocated internally, an attacker who can supply such a file can achieve memory corruption and potentially execute arbitrary code with the privileges of the running process.

Generated by OpenCVE AI on October 20, 2026 at 17:43 UTC.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Update Eclipse ThreadX – GUIX to a patched release that validates PNG chunk ordering.
  • Configure the application to reject PNG images containing a second IHDR chunk before decoding.
  • Temporarily disable PNG decoding functionality in the GUIX component until a patch is available.

Generated by OpenCVE AI on October 20, 2026 at 17:43 UTC.

Tracking

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Advisories

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History

Tue, 20 Oct 2026 16:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Tue, 20 Oct 2026 15:00:00 +0000

Type Values Removed Values Added
Description The PNG chunk reader has no notion of chunk ordering. It records whether an IDAT has been seen and whether a tRNS has already supplied transparency, but nothing prevents an IHDR being read a second time. A PNG carries exactly one IHDR and it is the first chunk. A file that places a second one after IDAT rewrites the image width, height, bit depth and pixel depth *after* the decoded-data buffer has already been allocated and filled from the original values. The pass that reverses the PNG row filters then derives its own extent from the new dimensions and walks the old allocation, moving image bytes past the end of it. The buffer is allocated by GUIX rather than supplied by the caller, so the application has no way to size it defensively. The decoder is compiled in by default.
Title PNG decoder: a duplicate IHDR chunk after IDAT resizes the image after allocation, causing a heap out-of-bounds write
Weaknesses CWE-125
CWE-787
References
Metrics cvssV4_0

{'score': 8.4, 'vector': 'CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}

Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: eclipse

Published:

Updated: 2026-10-20T15:28:59.237Z

Reserved: 2026-09-23T13:43:04.337Z

Link: CVE-2026-91186

cve-icon Vulnrichment

Updated: 2026-10-20T15:28:54.853Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-20T15:17:36.023

Modified: 2026-10-20T19:48:50.250

Link: CVE-2026-91186

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-20T17:45:13Z

Weaknesses