{"id":"CVE-2021-44228","kind":"vulnerability","aliases":["CVE-2021-44228"],"related":[],"title":"Apache Log4j2: Apache Log4j2 Remote Code Execution Vulnerability","description":"Apache Log4j2 2.0-beta9 through 2.15.0 (excluding security releases 2.12.2, 2.12.3, and 2.3.1) JNDI features used in configuration, log messages, and parameters do not protect against attacker controlled LDAP and other JNDI related endpoints. An attacker who can control log messages or log message parameters can execute arbitrary code loaded from LDAP servers when message lookup substitution is enabled. From log4j 2.15.0, this behavior has been disabled by default. From version 2.16.0 (along with 2.12.2, 2.12.3, and 2.3.1), this functionality has been completely removed. Note that this vulnerability is specific to log4j-core and does not affect log4net, log4cxx, or other Apache Logging Services projects.","summary":"Apache Log4j2 logging library evaluates JNDI lookups in logged messages, so attacker-controlled input can make the server load and run remote code. An attacker gets code execution on any server that logs their input.","severity":"critical","cvss":10.0,"epss":0.99999,"exploited":true,"exploited_at":"2021-12-10T00:00:00+00:00","products":[{"name":"Apache Log4j2","fixed":[],"affected":"","ecosystem":"vendor"}],"ecosystems":["vendor"],"tags":["enterprise","exploited","java","log4j","package","ransomware","self-hosted"],"not_affected_if":["no-log4j2-present","non-java-stack"],"how_to_check":"Search for log4j-core jars in application directories and fat jars (for example: find / -name 'log4j-core*.jar' 2>/dev/null) and check their version.","fix":"Upgrade log4j-core to a fixed release per the Apache Log4j2 security page; CISA requires applying updates or removing the affected asset.\nUntil patched, the CISA interim mitigations apply (see the CISA ED 22-02 mitigation page cited in the sources).","status":"open","published_at":"2021-12-10T00:00:00+00:00","first_seen_at":"2026-10-23T19:11:53+00:00","triaged_at":"2026-10-23T21:31:57+00:00","updated_at":"2026-10-23T21:57:35+00:00","category":"package","confidence":0.9,"triage":{"at":"2026-10-23T21:31:57Z","model":"claude-haiku-5-5","output":{"fix":"Upgrade log4j-core to a fixed release per the Apache Log4j2 security page; CISA requires applying updates or removing the affected asset.\nUntil patched, the CISA interim mitigations apply (see the CISA ED 22-02 mitigation page cited in the sources).","reach":"internet","impact":"high","summary":"Apache Log4j2 logging library evaluates JNDI lookups in logged messages, so attacker-controlled input can make the server load and run remote code. An attacker gets code execution on any server that logs their input.","category":"package","who_cares":["java","log4j","self-hosted","enterprise"],"confidence":0.9,"needs_auth":"no","worst_case":"Attacker runs arbitrary code on the server via a logged string","analyst_note":"Fixed version numbers and the exact mitigation steps are not in the sources; check the Apache Log4j2 security page and the CISA ED 22-02 link for affected and fixed versions.","how_to_check":"Search for log4j-core jars in application directories and fat jars (for example: find / -name 'log4j-core*.jar' 2>/dev/null) and check their version.\nunknown","needs_analyst":true,"not_affected_if":["no-log4j2-present","non-java-stack"],"user_interaction":"no","needs_special_setup":"no","severity_if_unknown":"critical"},"cost_usd":0.000528,"input_tokens":2950,"output_tokens":466,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2021':10A,13A '-44228':11A,14A '2.0':64C '2.12.2':71C,136C '2.12.3':72C,137C '2.15.0':67C,123C '2.16.0':133C '2.3.1':74C,139C 'affect':159C 'along':134C 'apach':1A,3A,26B,62C,164C 'apache':15A 'arbitrari':109C 'attack':38B,51B,88C,97C 'attacker-control':37B 'behavior':125C 'beta9':65C 'code':6A,49B,53B,110C 'complet':144C 'configur':79C 'control':39B,89C,100C 'core':155C 'cve':9A,12A 'default':130C 'disabl':128C 'enabl':120C 'endpoint':95C 'enterpris':17B 'evalu':30B 'exclud':68C 'execut':7A,54B,108C 'exploit':18B 'featur':76C 'function':141C 'get':52B 'host':25B 'input':40B,61B 'java':19B 'jndi':31B,75C,93C 'ldap':90C,113C 'librari':29B 'load':45B,111C 'log':28B,34B,59B,80C,101C,104C,165C 'log4cxx':161C 'log4j':20B,122C,154C 'log4j-core':153C 'log4j2':2A,4A,16A,27B,63C 'log4net':160C 'lookup':32B,117C 'make':42B 'messag':35B,81C,102C,105C,116C 'note':146C 'packag':21B 'paramet':83C,106C 'project':167C 'protect':86C 'ransomwar':22B 'relat':94C 'releas':70C 'remot':5A,48B 'remov':145C 'run':47B 'secur':69C 'self':24B 'self-host':23B 'server':44B,57B,114C 'servic':166C 'specif':151C 'substitut':118C 'use':77C 'version':132C 'vulner':8A,149C","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2021-12-10T00:00:00+00:00","kev":{"dateAdded":"2021-12-10","dueDate":"2021-12-24","requiredAction":"For all affected software assets for which updates exist, the only acceptable remediation actions are: 1) Apply updates; OR 2) remove affected assets from agency networks. Temporary mitigations using one of the measures provided at https://www.cisa.gov/uscert/ed-22-02-apache-log4j-recommended-mitigation-measures are only acceptable until updates are available.","knownRansomwareCampaignUse":"Known"},"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","cvss_by":"nvd@nist.gov","poc_count":0,"sources":[{"source":"kev","external_id":"CVE-2021-44228","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2021-44228","severity":null,"published_at":"2021-12-10T00:00:00+00:00","modified_at":null,"first_seen_at":"2026-10-23T19:11:53+00:00","fetched_at":"2026-10-25T13:39:32+00:00","note":null},{"source":"epss","external_id":"CVE-2021-44228","url":"https://api.first.org/data/v1/epss?cve=CVE-2021-44228","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-23T19:13:44+00:00","fetched_at":"2026-10-23T19:13:44+00:00","note":null},{"source":"nvd","external_id":"CVE-2021-44228","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-44228","severity":null,"published_at":"2021-12-10T10:15:09+00:00","modified_at":"2026-08-11T19:33:44+00:00","first_seen_at":"2026-10-23T21:57:35+00:00","fetched_at":"2026-10-23T21:57:35+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}