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Users are encouraged to consult the Log4j 1 to Log4j 2 migration guide https://logging.apache.org/log4j/2.x/migrate-from-log4j1.html , and specifically the section on eliminating reliance on the bridge."}], "id": "CVE-2026-34479", "lastModified": "2026-05-06T18:21:34.373", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 3.6, "source": "nvd@nist.gov", "type": "Primary"}], "cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 6.9, "baseSeverity": "MEDIUM", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "LOW", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "version": "4.0", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "security@apache.org", "type": "Secondary"}]}, "published": "2026-04-10T16:16:31.270", "references": [{"source": "security@apache.org", "tags": ["Exploit", "Issue Tracking", "Patch"], "url": "https://github.com/apache/logging-log4j2/pull/4078"}, {"source": "security@apache.org", "tags": ["Mailing List"], "url": "https://lists.apache.org/thread/gd0hp6mj17rn3kj279vgy4p7kd4zz5on"}, {"source": "security@apache.org", "tags": ["Vendor Advisory"], "url": "https://logging.apache.org/cyclonedx/vdr.xml"}, {"source": "security@apache.org", "tags": ["Mitigation"], "url": "https://logging.apache.org/log4j/2.x/migrate-from-log4j1.html"}, {"source": "security@apache.org", "tags": ["Vendor Advisory"], "url": "https://logging.apache.org/security.html#CVE-2026-34479"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Mailing List"], "url": "http://www.openwall.com/lists/oss-security/2026/04/10/8"}], "sourceIdentifier": "security@apache.org", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-116"}], "source": "security@apache.org", "type": "Secondary"}]}

{"bugzilla": {"description": "org.apache.logging.log4j/log4j-1.2-api: Apache Log4j 1-to-Log4j 2 bridge: Log processing denial of service due to improper XML escaping", "id": "2457313", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2457313"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.3", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L", "status": "draft"}, "cwe": "CWE-91", "details": ["A flaw was found in the Apache Log4j 1-to-Log4j 2 bridge. The Log4j1XmlLayout component fails to properly escape characters forbidden by the XML 1.0 standard. This improper handling of characters results in malformed XML output, which can cause downstream log processing systems to drop or fail to index affected records. The primary consequence is a denial of service for log analysis, potentially hindering security monitoring and incident response."], "mitigation": {"lang": "en:us", "value": "Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability."}, "name": "CVE-2026-34479", "package_state": [{"cpe": "cpe:/a:redhat:jboss_data_grid:8", "fix_state": "Fix deferred", "package_name": "log4j-1.2-api", "product_name": "Red Hat Data Grid 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "log4j:2/log4j", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "log4j", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:jboss_fuse:7", "fix_state": "Fix deferred", "package_name": "log4j-1.2-api", "product_name": "Red Hat Fuse 7"}, {"cpe": "cpe:/a:redhat:jboss_enterprise_application_platform:7", "fix_state": "Fix deferred", "package_name": "log4j-1.2-api", "product_name": "Red Hat JBoss Enterprise Application Platform 7"}, {"cpe": "cpe:/a:redhat:jboss_enterprise_application_platform:8", "fix_state": "Fix deferred", "package_name": "log4j-1.2-api", "product_name": "Red Hat JBoss Enterprise Application Platform 8"}, {"cpe": "cpe:/a:redhat:jbosseapxp", "fix_state": "Fix deferred", "package_name": "log4j-1.2-api", "product_name": "Red Hat JBoss Enterprise Application Platform Expansion Pack"}, {"cpe": "cpe:/a:redhat:offline_knowledge_portal:1", "fix_state": "Fix deferred", "package_name": "redhat-user-workloads/rhokp-core-encrypted", "product_name": "Red Hat Offline Knowledge Portal"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-modelmesh-rhel8", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-modelmesh-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:amq_streams:3", "fix_state": "Fix deferred", "package_name": "log4j-1.2-api", "product_name": "streams for Apache Kafka 3"}], "public_date": "2026-04-10T15:41:07Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-34479\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-34479\nhttps://github.com/apache/logging-log4j2/pull/4078\nhttps://lists.apache.org/thread/gd0hp6mj17rn3kj279vgy4p7kd4zz5on\nhttps://logging.apache.org/cyclonedx/vdr.xml\nhttps://logging.apache.org/log4j/2.x/migrate-from-log4j1.html\nhttps://logging.apache.org/security.html#CVE-2026-34479"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[2.7,2.25.4)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[3.0.0-alpha1,3.0.0-beta2]"}}], "enrichment": {"confidence": 100.0, "confidence_source": "manual", "scores": [{"score": 100.0, "source": "manual"}]}, "original": {"product": "Apache Log4j 1 to Log4j 2 bridge", "source": "cna", "vendor": "Apache Software Foundation"}, "product": "log4j", "vendor": "apache"}], "analysis": {"en": {"generated_at": "2026-04-14T02:07:02.903844+00:00", "value": {"mitigation_remediation": ["Upgrade the Apache Log4j 1-to-Log4j 2 bridge to version 2.25.4 or later.", "If the bridge is no longer needed, remove it from the application to eliminate the vulnerability.", "Disable Log4j1XmlLayout or the XMLLayout class when they are not required.", "Verify that downstream log processing systems correctly handle escaped characters and monitor for missing events.", "Follow the Log4j 1 to Log4j 2 migration guide to phase out the bridge entirely."], "summary": {"action": "Patch Upgrade", "impact": "Silent log event loss via malformed XML"}, "threat_synthesis": {"affected_systems": "Deployments using the Apache Log4j 1-to-Log4j 2 bridge are vulnerable. This includes configurations that employ Log4j1XmlLayout directly in Log4j Core 2, and those that use the Log4j 1 compatibility layer with org.apache.log4j.xml.XMLLayout. The vulnerability applies to any version prior to the corrected 2.25.4 release; no specific older version range is listed.", "description_and_impact": "The Log4j1XmlLayout component fails to escape characters forbidden by XML 1.0, producing malformed XML logs. Conforming parsers reject such documents with a fatal error, causing downstream log processing to drop or fail to index these events. The defect does not provide arbitrary code execution but leads to loss of audit data, reducing the integrity of logs.", "risk_and_exploitability": "The CVSS score of 6.9 indicates medium severity, and the EPSS score of less than 1% suggests a low probability of exploitation. The CVE is not in the CISA KEV catalog. Based on the description, it is inferred that an attacker would need the ability to inject log entries containing XML\u2011forbidden characters, typically by influencing application input that is logged. No remote code execution or elevated privilege is required, so the risk of exploitation remains relatively low, but the loss of logs can impair incident response and compliance."}}}}, "created": "2026-04-13T12:44:43.077727+00:00", "updated": "2026-04-14T16:36:25.795140+00:00", "vendors": ["apache", "apache$PRODUCT$log4j"]}