Predator and CL did not provide any possible suspects.
Using Code Search for the file, "xmlstring.c" assigning to the concern owner.
Suspecting Commit#
https://chromium.googlesource.com/chromium/src/+/3c53598f981660671a93f9f71e52e5bb58a2b64e

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

Yes, I maintain integrating this third party library.

Unfortunately there are more pressing problems than leaks in libxml, and fixing leaks may exacerbate them--it's safer to leak something than to not hold onto it long enough--so let's keep this open but I will lower the priority.

ClusterFuzz has detected this issue as fixed in range 480710:480765.

Detailed report: https://clusterfuzz.com/testcase?key=6523562581295104

Fuzzer: libFuzzer_libxml_xml_read_memory_fuzzer
Job Type: libfuzzer_chrome_asan_debug
Platform Id: linux

Crash Type: Direct-leak
Crash Address: 
Crash State:
  xmlStrndup
  xmlStrdup
  xmlBufAttrSerializeTxtContent
  
Sanitizer: address (ASAN)

Regressed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan_debug&range=450685:450714
Fixed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_asan_debug&range=480710:480765

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=6523562581295104


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 6523562581295104 is verified as fixed, so closing issue.

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