CVE-2026-121250
Description
An use after free flaw was found in the Extensions 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 restrict extension installation and block untrusted extensions within the Chromium browser environment: upgrade to Chromium 157.0.8103.38 (or the fixed Chromium builds), which resolves use-after-free memory corruption within the Chromium Extensions component, closing crafted Chrome extension. Until patched, this is a concern on Chromium-based browser installations running versions prior to 157.0.8103.38, so restrict and policy-block the installation or sideloading of third-party extensions, and educate users against social engineering lures prompting extension installation. As a compensating measure, Enable Address Space Layout Randomization to randomize memory layout and obstruct reuse of freed object pointers and gadget locations, Enforce Non-Executable Memory (NX/XD bit) to block direct shellcode execution in heap and data memory pages, Enable Full RELRO and PIE to maintain a read-only Global Offset Table and prevent GOT pointer overwrites, Enforce Control Flow Integrity and Shadow Call Stack to validate indirect branch targets during control-flow hijacking attempts, and Deploy EDR agents to detect and terminate unauthorized processes spawned outside the browser sandbox. 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-101 ASLR (Address Space Layout Randomization) (medium)
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.
Frequently Asked Questions
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