Predator and CL could not provide any possible suspects.
Using Code Search for the file, "third_party/libxml/src/parser.c" assigning to the concern owner who might be related.

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

Automatically applying components based on information from OWNERS files. If this seems incorrect, please apply the Test-Predator-Wrong-Components label.

Reproduced locally.  Program runs OK with 64MB stack.  Direct duplicate of  issue 768151 .

ClusterFuzz has detected this issue as fixed in range 509030:509045.

Detailed report: https://clusterfuzz.com/testcase?key=5280149506621440

Fuzzer: libFuzzer_libxml_xml_read_memory_fuzzer
Job Type: libfuzzer_chrome_asan_debug
Platform Id: linux

Crash Type: Stack-overflow
Crash Address: 0x7ffd5d5eea68
Crash State:
  xmlParseConditionalSections
  
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=509030:509045

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=5280149506621440

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.