CVE-2026-121166
Description
A type confusion flaw was found in the PDFium component of the Chromium browser.
Upstream bug(s):
Statement
Red Hat Product Security rates the severity of this flaw as determined by the Google Chrome Security Advisory.
Mitigation
--- CME Mitigation Guidance (2026-11-04) ---
Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure.
The highest-value action is to enforce control flow integrity on PDFium indirect calls and virtual table dispatches within the browser sandbox: upgrade to Google Chrome 157.0.8103.38+ (or the fixed Chromium builds), which corrects type handling during PDF parsing within the PDFium component, closing crafted PDF file. Until patched, this is a concern on Chromium and Google Chrome deployments on any platform processing PDF documents, so restrict opening untrusted PDF files in Chromium and prevent processing documents from unverified sources. As a compensating measure, ensure address space layout randomization is active to force an information leak before control-flow hijack payloads can be constructed and enforce non-executable memory on data pages to prevent direct shellcode execution in heap or stack memory. These controls limit blast radius and contain exploitation, but they do not fix the underlying type confusion defect — apply the upstream patch to fully remediate.
Highest-impact CME: CME-113 Control Flow Integrity (CFI / Shadow Call Stack) (high)
Understanding the Weakness (CWE)
Other
Technical Impact: Varies by Context
When the product accesses the resource using an incompatible type, this could trigger logical errors because the resource does not have expected properties.
Availability,Integrity,Confidentiality
Technical Impact: Read Memory; Modify Memory; Execute Unauthorized Code or Commands; DoS: Crash, Exit, or Restart
If a memory buffer is accessed using an incompatible type, and the allocated buffer is smaller than the type that the code is attempting to access, then an attacker could read or write memory outside the bounds of the buffer, leading to a crash or possibly code execution.
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