From the regression range, https://chromium-review.googlesource.com/564016 is the most likely culprit but I am not convinced.

This is a serious security regression. If you are not able to fix this quickly, please revert the change that introduced it.

If this doesn't affect a release branch, or has not been properly classified for severity, please update the Security_Impact or Security_Severity labels, and remove the ReleaseBlock label. To disable this altogether, apply ReleaseBlock-NA.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

ClusterFuzz has detected this issue as fixed in range 492717:492757.

Detailed report: https://clusterfuzz.com/testcase?key=6116638729699328

Fuzzer: inferno_twister
Job Type: mac_asan_content_shell
Platform Id: mac

Crash Type: Use-after-poison READ 4
Crash Address: 0x7ee0ab6780b4
Crash State:
  blink::EventListenerIterator::NextListener
  blink::EventTarget::TraceWrappers
  blink::TraceTrait<blink::Clipboard>::TraceMarkedWrapper
  
Sanitizer: address (ASAN)

Recommended Security Severity: High

Regressed: https://clusterfuzz.com/revisions?job=mac_asan_content_shell&range=489687:489692
Fixed: https://clusterfuzz.com/revisions?job=mac_asan_content_shell&range=492717:492757

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=6116638729699328


See https://github.com/google/clusterfuzz-tools for more information.

If you suspect that the result above is incorrect, try re-doing that job on the test case report page.

ClusterFuzz testcase 6116638729699328 is verified as fixed, so closing issue as verified.

If this is incorrect, please add ClusterFuzz-Wrong label and re-open the issue.

This bug has been closed for more than 14 weeks. Removing security view restrictions.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot