Apache software foundation apache log4j2, improper input validation: 3 records, one defect family
Apache software foundation apache log4j2 has been reported 3 separate times for the same kind of mistake, CWE-20, between 2021-12-10 and 2021-12-28. A defect family is our own grouping of the CVE corpus: every record naming one product and one weakness class, collected so a repeat is visible as a repeat. No public source publishes this, and what this page counts is how often this one product has gone wrong in this one way.
What this page is, and what it is not
The records are public. This grouping is not. No source publishes defect families, so we built them: every record in the corpus sorted by the product an authority named and the weakness class carried with it, 21316 families over 105586 records. This one holds every record that names Apache software foundation apache log4j2 and carries CWE-20, matched character for character. We show the join because a grouping you cannot check is a grouping you should not cite.
That is 3 filings, between 2021-12-10 and 2021-12-28, landing on the same weakness class in the same product. At this count it is a repeat rather than a pattern, and the roster below is short enough to read in full. This is what we held on 2026-09-20.
A repeat is evidence about where to look. If you are reviewing Apache software foundation apache log4j2, the records below say which mistake has already been found more than once, which is the cheapest place a reviewer can start. If you are asking the vendor a question, a count under one weakness class is a better question than any single record is.
What this page cannot tell you is decided by what was joined. A product name and a weakness class settled membership, so those two values are the whole of what the page asserts. Records here may sit in the same line of code or in unrelated parts of the product, and we hold no value that separates those cases. A fixed version named in one record closes that record and says nothing about the others. And nothing here describes anyone's systems, because no value in this family connects a product name to an installation.
The names the authorities used
One spelling, used by every authority that filed one of these records: apache software foundation apache log4j2.
These records name more than one weakness class each. All 3 carry CWE-20, which is what this family was grouped on, and one of them also names CWE-400, uncontrolled resource consumption. The roster below shows what each record names; both readings are the record's own, filed together by the same authority. 3 other classes appear across the family as well.
Family membership: held values. Joined on the product and weakness class the assigning authorities wrote, with no model involved.
What the records offer
All 3 records publish a fixed version.
1 record is listed by CISA with a required action, which carries a federal remediation deadline on its own page.
The earliest was published 2021-12-10 and the latest 2021-12-28. That span is how long this product kept producing this weakness, not how long any one record took to fix.
What this page does not cover
This is a family of records that read alike. It is not a shared vulnerability, not an inventory, and not a statement that one fix closes the rest. Each record's own state, its own dates and its own receipts are on its own page.
Grouped by shared product and weakness, not by shared vulnerability. Each record's own state is on its own page.
Everything this vendor has, including records outside this family:
3 records, read from the index as it stood on 20 Sep 2026. Every row opens the record it names, and every value on that record opens its own receipt.