Apache Log4j vulnerabilities: known CVEs & security history
Apache · Dev / Logging · 10 tracked CVEs · 1 actively exploited · updated November 2026 · what is a CVE? →
This is the full list of known vulnerabilities (CVEs) across all Apache Log4j release lines — 10 in total, with 1 actively exploited in the wild. A CVE here doesn't mean your version is affected — check Apache Log4j's current status and the safe version to run.
Known Apache Log4j CVEs
Actively-exploited and most-severe first. Open any CVE for full details.
| CVE | Severity | CVSS | EPSS | Year |
|---|---|---|---|---|
| CVE-2021-44228⚡ exploited | critical | 10 | 100% | 2021 |
| CVE-2020-9493 | critical | 9.8 | 5% | 2021 |
| CVE-2017-5645 | critical | 9.8 | 90% | 2017 |
| CVE-2026-34481 | high | 7.5 | 1% | 2026 |
| CVE-2026-34480 | high | 7.5 | 1% | 2026 |
| CVE-2026-34479 | high | 7.5 | 1% | 2026 |
| CVE-2026-34478 | high | 7.5 | 1% | 2026 |
| CVE-2026-49844 | medium | 5.9 | 1% | 2026 |
| CVE-2026-34477 | medium | 5.9 | 1% | 2026 |
| CVE-2021-45105 | medium | 5.9 | 100% | 2021 |
Is my Apache Log4j version affected?
The list above spans every release. To know whether your version is affected — and the minimum safe version to upgrade to — check it directly.
Check your Apache Log4j version → · Monitor Apache Log4j for new CVEs →
Apache Log4j vulnerabilities — frequently asked
How many known vulnerabilities does Apache Log4j have?
IsItPatched tracks 10 CVEs for Apache Log4j, 1 of which is actively exploited (CISA KEV). 3 are critical-severity and 4 high-severity. These span every release line — what matters is whether the version you run is affected.
Does Apache Log4j have any actively-exploited vulnerabilities?
Yes — 1 Apache Log4j CVE is in CISA's Known Exploited Vulnerabilities catalog, meaning it is confirmed exploited in the wild (1 linked to ransomware). Patch it as a priority.
What is the most severe Apache Log4j vulnerability?
Among tracked issues, CVE-2021-44228 (CRITICAL, CVSS 10), which is actively exploited, ranks highest — a Improper input validation weakness.
Is Apache Log4j safe to use?
It depends on the version. The latest supported Apache Log4j release (2.26.1) clears the known issues; older versions may still be affected. Check the exact version you run for a verdict.
CVE data aggregated from NVD, CISA KEV and EPSS (FIRST.org). Related: Apache Log4j security status · Apache Log4j end-of-life · actively-exploited CVEs. Always verify against Apache's advisories — see our disclaimer.