CVE-2026-121123
Description
An use after free flaw was found in the Canvas 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 prevent dereferencing of freed memory in the Canvas component during page rendering: upgrade to Google Chrome 157.0.8103.38 (or the fixed Chromium builds), which corrects memory management to prevent access to freed Canvas objects during rendering, closing crafted HTML page. Until patched, this is a concern on Chromium browser instances rendering untrusted web content, so restrict browser navigation to trusted web pages and isolate or block untrusted HTML content. As a compensating measure, ensure ASLR is active across renderer processes to randomize address space and impede gadget placement, enforce non-executable memory permissions on heap and data pages to prevent shellcode execution, and maintain full RELRO and PIE enforcement to protect relocation tables from post-corruption overwrites. These controls limit blast radius and contain exploitation, but they do not fix the underlying use-after-free 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)
Integrity
Technical Impact: Modify Memory
The use of previously freed memory may corrupt valid data, if the memory area in question has been allocated and used properly elsewhere.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If chunk consolidation occurs after the use of previously freed data, the process may crash when invalid data is used as chunk information.
Confidentiality
Technical Impact: Read Memory
Read operations on freed memory can sometimes leak sensitive information instead of causing a crash
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If malicious data is entered before chunk consolidation can take place, it may be possible to take advantage of a write-what-where primitive to execute arbitrary code. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.
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