PNG decoder: a duplicate IHDR chunk after IDAT resizes the image after allocation, causing a heap out-of-bounds write

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-91186
StatePUBLISHED
Assignereclipse
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-20 15:17:36 UTC
Updated2026-10-20 19:48:50 UTC
DescriptionThe 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.

Risk And Classification

Primary CVSS: v4.0 8.4 HIGH from [email protected]

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Problem Types: CWE-125 | CWE-787 | CWE-125 CWE-125 Out-of-bounds Read | CWE-787 CWE-787 Out-of-bounds Write

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary8.4HIGHCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/C...
4.0CNACVSS8.4HIGHCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS v4.0 Breakdown

Attack Vector
Local
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
Active
Confidentiality
High
Integrity
High
Availability
High
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Eclipse Foundation Eclipse ThreadX - GUIX affected 6.5.1.202602a semver Not specified
CNA Eclipse Foundation Eclipse ThreadX - GUIX unaffected 6.5.2.202603 Not specified

References

ReferenceSourceLinkTags
github.com/eclipse-threadx/guix/security/advisories/GHSA-gx8f-4rpc-4fjw [email protected] github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Kimdir01 (en)

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