critical Known exploitedREV. 01
CVE-2021-44228Log4Shell — Log4j Lookup Leads to Remote Code Execution
A logging library resolves lookups inside the text it is asked to log, so any attacker-controlled string that reaches a log line — a username, a header — makes the server fetch and run remote code.
Read the risk
THE VITAL STATS- CVSS score
- 10.0/ 10 CVSS v3.1
- EPSS probability
- 100% Likelihood of exploitation
- Attack complexity
- Low Conditions needed to exploit
- Known exploited
- Yes — CISA KEV
- CVE published
- 2021-12-10
- Added to KEV
- 2021-12-10
- Exploit published
- Yes
- Confidence
- high
- Kill chain
- initial access
- MITRE ATT&CK
- T1190, T1059
- Severity
- critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Attacker needsAny input that reaches a log statement
Behind the card
5 REFERENCES- 01CVE recordNVD recordnvd.nist.gov
- 02CISACISA Known Exploited Vulnerabilities catalogcisa.gov
- 03Vendor advisoryopenwall.comopenwall.com
- 04Vendor advisoryopenwall.comopenwall.com
- 05Vendor advisorylogging.apache.orglogging.apache.org
Field-level provenanceTRACE THE SOURCES +
Which source supports each field, when it was retrieved, and who extracted it.
| Fields | Source | Retrieved | Extractor | Confidence |
|---|---|---|---|---|
| cvss, exploitation.attack_complexity, exploitation.exploit_available, references, published_at | nvd.nist.gov | 2026-08-07 | scrty-crds-pipeline/0.1 | high |
| exploitation.known_exploited, exploitation.kev_added | cisa.gov | 2026-08-07 | scrty-crds-pipeline/0.1 | high |
| epss | api.first.org | 2026-08-07 | scrty-crds-pipeline/0.1 | high |
| title, summary, severity, remediation, mitre_attack, kill_chain, recommended_action, confidence, tags, exploitation.prerequisites | nvd.nist.gov | 2026-08-07 | claude-code | high |
Printing history
THE RECORD- r1Recommended action revised; Summary rewritten; Fixed versions updated
- r3Initial base card