Predator and CL did not provide any possible suspects.
Using Code Search for the file, "CXFA_Node::InsertChild" assigning to the concern owner and related Dev in Cc.

@tsepez -- Could you please look into the issue, kindly re-assign if this is not related to your changes.
Thank You.

ClusterFuzz has detected this issue as fixed in range 463054:463440.

Detailed report: https://clusterfuzz.com/testcase?key=4979130518208512

Fuzzer: libfuzzer_pdfium_xfa_fuzzer
Job Type: libfuzzer_chrome_asan_debug
Platform Id: linux

Crash Type: ASSERT
Crash Address: 
Crash State:
  false
  CXFA_Node::InsertChild
  CXFA_SimpleParser::ParseAsXDPPacket_XDP
  
Sanitizer: address (ASAN)

Regressed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan_debug&range=463017:463054
Fixed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan_debug&range=463054:463440

Reproducer Testcase: https://clusterfuzz.com/download/AMIfv94clU0rOjOtxQlszfvyH6dZAULA3yK-_WhZT1257eBzR-V9ONMFdXpBKr-ByDwP3UrVg-07UJ-Yz0kcLmkXSu-_lgDJLVAK0kqFUm1tRV7fMndZizG4yqHvYT6YXVgnlG7GM2QOkSEafZM2N-XiEMJiqTBvutad1rwdpukrvoRoSJ-02kS2hXNoA-u7Y-aR5tzlnEKhAfyEKB1eNJXBtnbQCnDONSSuOornwcsygS9-kZV_Xbp-At-DviIMcW5JWbqpAOhiQC4eX4-WqR5ekDVPm_-d9ZlrGo8Oqcxl3cqdZCo4MAzDhraPDY0HpleCEHgTCBMl0dHX6UWVVkG1Z9fmOWWJXC_sHmMIJyb_UeMq5NUdGQE?testcase_id=4979130518208512


See https://chromium.googlesource.com/chromium/src/+/master/testing/libfuzzer/reproducing.md 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 4979130518208512 is verified as fixed, so closing issue.

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

I don't think this is fixed, we should verify before closing.

CL at https://pdfium-review.googlesource.com/4390

We have made a bunch of changes on ClusterFuzz side, so resetting ClusterFuzz-Wrong label.