{"cve":"CVE-2026-34477","nvd":{"published":"2026-04-10T16:16:30.843","modified":"2026-10-26T22:10:00.163","status":"Analyzed","description":"The fix for  CVE-2025-68161 https://logging.apache.org/security.html#CVE-2025-68161  was incomplete: it addressed hostname verification only when enabled via the  log4j2.sslVerifyHostName https://logging.apache.org/log4j/2.x/manual/systemproperties.html#log4j2.sslVerifyHostName  system property, but not when configured through the  verifyHostName https://logging.apache.org/log4j/2.x/manual/appenders/network.html#SslConfiguration-attr-verifyHostName  attribute of the <Ssl> element.\n\nAlthough the verifyHostName configuration attribute was introduced in Log4j Core 2.12.0, it was silently ignored in all versions through 2.25.3, leaving TLS connections vulnerable to interception regardless of the configured value.\n\nA network-based attacker may be able to perform a man-in-the-middle attack when all of the following conditions are met:\n\n  *  An SMTP, Socket, or Syslog appender is in use.\n  *  TLS is configured via a nested <Ssl> element.\n  *  The attacker can present a certificate issued by a CA trusted by the appender's configured trust store, or by the default Java trust store if none is configured.\nThis issue does not affect users of the HTTP appender, which uses a separate  verifyHostname https://logging.apache.org/log4j/2.x/manual/appenders/network.html#HttpAppender-attr-verifyHostName  attribute that was not subject to this bug and verifies host names by default.\n\nUsers are advised to upgrade to Apache Log4j Core 2.25.4, which corrects this issue.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:L/SA:N","score":6.3},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N","score":5.9},"cwes":["CWE-295","CWE-297"],"references":["https://github.com/apache/logging-log4j2/pull/4075","https://lists.apache.org/thread/lkx8cl46t2bvkcwfcb2pd43ygc097lq4","https://logging.apache.org/cyclonedx/vdr.xml","https://logging.apache.org/log4j/2.x/manual/appenders/network.html#SslConfiguration-attr-verifyHostName","https://logging.apache.org/security.html#CVE-2026-34477"],"products":["apache:log4j"],"source":"nvd","synced_at":"2026-10-26T22:26:44.656832877+00:00"},"epss":{"cve":"CVE-2026-34477","score":0.0056,"percentile":0.46326,"date":"2026-10-26"},"kev":null,"osv":[{"id":"GHSA-6hg6-v5c8-fphq","url":"https://osv.dev/vulnerability/GHSA-6hg6-v5c8-fphq","summary":"Apache Log4j Core: `verifyHostName` attribute silently ignored in TLS configuration","modified":"2026-09-10T03:50:43.570169134Z","packages":[{"ecosystem":"Maven","name":"org.apache.logging.log4j:log4j-core","purl":"pkg:maven/org.apache.logging.log4j/log4j-core","ranges":[">=2.12.0 <2.25.4"],"fixed":["2.25.4"]},{"ecosystem":"Maven","name":"org.apache.logging.log4j:log4j-core","purl":"pkg:maven/org.apache.logging.log4j/log4j-core","ranges":[">=3.0.0-alpha1 <=3.0.0-beta3"],"fixed":[]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}