CVE Explorer
CVE-2026-34480
Apache Log4j Core's XmlLayout https://logging.apache.org/log4j/2.x/manual/layouts.html#XmlLayout , in versions up to and including 2.25.3, fails to sanitize characters forbidden by the XML 1.0 specification https://www.w3.org/TR/xml/#charsets producing invalid XML output whenever a log message or MDC value contains such characters.
The impact depends on the StAX implementation in use:
* JRE built-in StAX: Forbidden characters are silently written to the output, producing malformed XML. C
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
0
Affected products and versions
1 source assertion{"collectionURL":"https://repo.maven.apache.org/maven2","cpes":["cpe:2.3:a:apache:log4j:*:*:*:*:*:*:*:*"],"defaultStatus":"unaffected","packageName":"org.apache.logging.log4j:log4j-core","packageURL":"pkg:maven/org.apache.logging.log4j/log4j-core","product":"Apache Log4j Core","vendor":"Apache Software Foundation","versions":[{"lessThan":"2.25.4","status":"affected","version":"2.0-alpha1","versionType":"maven"},{"lessThanOrEqual":"3.0.0-beta3","status":"affected","version":"3.0.0-alpha1","versionType":"maven"}]}
- cve_program_cvelist_v5affectedurn:baitaphish:normalized-source-record:v2:d6a20e36e3ee08ae06f40fae68c6b47eabc3a7202470a68c44b837ccc4225749 · sha256:d9fc98a6e47a0df6… · /containers/cna/affected/0
Provider-owned CVSS observations
1 source assertion{"metric":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"NETWORK","baseScore":6.9,"baseSeverity":"MEDIUM","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","version":"4.0","vulnAvailabilityImpact":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NO…
- cve_program_cvelist_v5cvssurn:baitaphish:normalized-source-record:v2:d6a20e36e3ee08ae06f40fae68c6b47eabc3a7202470a68c44b837ccc4225749 · sha256:d9fc98a6e47a0df6… · /containers/cna/metrics/0/cvssV4_0
CWE assertions
1 source assertion{"cweId":"CWE-116","description":"CWE-116 Improper Encoding or Escaping of Output","lang":"en","type":"CWE"}
- cve_program_cvelist_v5cweurn:baitaphish:normalized-source-record:v2:d6a20e36e3ee08ae06f40fae68c6b47eabc3a7202470a68c44b837ccc4225749 · sha256:d9fc98a6e47a0df6… · /containers/cna/problemTypes/0/descriptions/0
Source references
6 source assertions{"url":"http://www.openwall.com/lists/oss-security/2026/04/10/9"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:d6a20e36e3ee08ae06f40fae68c6b47eabc3a7202470a68c44b837ccc4225749 · sha256:d9fc98a6e47a0df6… · /containers/adp/0/references/0
{"tags":["patch"],"url":"https://github.com/apache/logging-log4j2/pull/4077"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:d6a20e36e3ee08ae06f40fae68c6b47eabc3a7202470a68c44b837ccc4225749 · sha256:d9fc98a6e47a0df6… · /containers/cna/references/0
{"tags":["vendor-advisory"],"url":"https://lists.apache.org/thread/5x0hcnng0chhghp6jgjdp3qmbbhfjzhb"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:d6a20e36e3ee08ae06f40fae68c6b47eabc3a7202470a68c44b837ccc4225749 · sha256:d9fc98a6e47a0df6… · /containers/cna/references/4
{"tags":["vendor-advisory"],"url":"https://logging.apache.org/cyclonedx/vdr.xml"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:d6a20e36e3ee08ae06f40fae68c6b47eabc3a7202470a68c44b837ccc4225749 · sha256:d9fc98a6e47a0df6… · /containers/cna/references/2
{"tags":["related"],"url":"https://logging.apache.org/log4j/2.x/manual/layouts.html#XmlLayout"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:d6a20e36e3ee08ae06f40fae68c6b47eabc3a7202470a68c44b837ccc4225749 · sha256:d9fc98a6e47a0df6… · /containers/cna/references/3
{"tags":["vendor-advisory"],"url":"https://logging.apache.org/security.html#CVE-2026-34480"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:d6a20e36e3ee08ae06f40fae68c6b47eabc3a7202470a68c44b837ccc4225749 · sha256:d9fc98a6e47a0df6… · /containers/cna/references/1
Attribution and limitations
- CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →
Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.