CVE-2026-34480 Apache Log4j
| Affected software | Apache Log4j |
|---|---|
| Severity | 6.9 Medium CVSS 4.0 2 scores |
| Fixed in | 2.25.4 |
| Weakness | CWE-116 |
| Published | 10 Apr 2026 |
| Updated | 26 Oct 2026 |
Description
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. Conforming parsers must reject such documents with a fatal error, which may cause downstream log-processing systems to drop the affected records. * Alternative StAX implementations (e.g., Woodstox https://github.com/FasterXML/woodstox , a transitive dependency of the Jackson XML Dataformat module): An exception is thrown during the logging call, and the log event is never delivered to its intended appender, only to Log4j's internal status logger. Users are advised to upgrade to Apache Log4j Core 2.25.4, which corrects this issue by sanitizing forbidden characters before XML output.
Exploitation status
No public exploit
No exploit has been reported in the sources we check.
Exploitation status
- CISA KEV not listed
- VulnCheck KEV not listed
- CISA Vulnrichment exploitation: none
- Indexed PoC none indexed
- EPSS 1.1% chance in 30 days
Waratek protection
Within Waratek scope. In the sources we check, nobody has published exploit code for this CVE or reported it being exploited.
A public code fix exists: apache/logging-log4j2 #4077.
- Protection none
- Action unverified
- Review automated Upstream data
- Record active
| Decided by | Exploit code for this candidate, published in a reviewed catalogue or a GitHub repository with 5 or more stars, or in use per CISA or VulnCheck; not only a CISA verdict, a forecast, or nothing at all |
|---|---|
| Finding | This CVE is not listed in CISA KEV or VulnCheck KEV, CISA Vulnrichment records no active exploitation, no reviewed exploit catalogue carries an entry for it, and no GitHub PoC repository for it has 5 or more stars. Nobody has published exploit code worth tracing, so it is not a candidate for a rule ahead of the ones where somebody has; an upstream fix path does exist, so the remediation half of the candidacy still holds. This is a statement about what has been published, not about whether the defect is reachable or serious. |
| Candidate fix | https://github.com/apache/logging-log4j2/pull/4077 : a pull request: the change under review |
CVSS
6.9 MEDIUM
v4.0 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
2 metrics
CVSS
6.9 MEDIUM v4.0CVSS: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
2 metrics
We show the highest score from the newest CVSS version. Scores from different versions can't be compared, and the first score listed is sometimes a 0.0 placeholder.
| Version | Score | Band | Vector | Assigner | Type | |
|---|---|---|---|---|---|---|
| CVSS 4.0 | 6.9 | MEDIUM | 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 |
security@apache.org | Secondary | published |
| CVSS 3.1 | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |
NVD | Primary |
Affected software and releases
Oracle advisories
| Advisory | Type | Quarter | Products Oracle names in its risk matrix |
|---|---|---|---|
| Oracle Critical Patch Update October 2026 ↗ | CPU | 2026-Q4 | Oracle Siebel CRM / Siebel Approval Manager (Apache Log4j) (17.0-26.8) |
| Oracle Critical Patch Update July 2026 ↗ | CPU | 2026-Q3 | Oracle Analytics / Platform Security (Apache Log4j) (8.2.0.0.0, 26.01.0.0.0) Oracle Communications / Core (Apache Log4j) (6.1.1-7.0.0) Oracle Fusion Middleware / Third Party Analysis Tool (Apache Log4j) (12.2.1.4.0) |
| Oracle Critical Security Patch Update August 2026 ↗ | CSPU | 2026-Q3 | Oracle Enterprise Manager / EM Plugin: General (Apache Log4j) (13.5.1.0.0-13.5.6.0.0) Oracle Financial Services Applications / ECM (Apache Log4j) (8.0.8.2, 8.1.2.11) Oracle Financial Services Applications / Third Party (Apache Log4j) (8.0.8.1, 8.1.2.11) Oracle Financial Services Applications / User Interface (Apache Log4j) (8.0.8.0) Oracle Hyperion / Installation/Configuration (Apache Log4j) (11.2.25.0.000) Oracle Retail Applications / Application Core (Apache Log4j) (15.0, 16.0) Oracle Retail Applications / NF Issuing (Apache Log4j) (14.2) Oracle Retail Applications / Operations & Maintenance (Apache Log4j) (15.0, 16.0) Oracle Supply Chain / CAX Client (Apache Log4j) (3.6) |
| Oracle Critical Security Patch Update September 2026 ↗ | CSPU | 2026-Q3 | Oracle Financial Services Applications / Infrastructure (Apache Log4j) (14.5.0.0.0-14.9.0.0.0) |
| Oracle Critical Security Patch Update June 2026 ↗ | CSPU | 2026-Q2 | Oracle Communications / Other (Apache Log4j) (7.3.6, 7.4.0, 7.5.0, 8.0.0) Oracle Enterprise Manager / Agent Next Gen (Apache Log4j) (13.5, 24.1) |
Oracle components and versions
| Family | Component | Versions, as Oracle lists them | Read as |
|---|---|---|---|
| Oracle Analytics | Platform Security (Apache Log4j) | 8.2.0.0.0, 26.01.0.0.0 | 8.2.0.0.0 · 26.1.0.0.0 |
| Oracle Communications | Core (Apache Log4j) | 6.1.1-7.0.0 | |
| Oracle Communications | Other (Apache Log4j) | 7.3.6, 7.4.0, 7.5.0, 8.0.0 | 7.3.6 · 7.4.0 · 7.5.0 · 8.0.0 |
| Oracle Enterprise Manager | Agent Next Gen (Apache Log4j) | 13.5, 24.1 | 13.5 · 24.1 |
| Oracle Enterprise Manager | EM Plugin: General (Apache Log4j) | 13.5.1.0.0-13.5.6.0.0 | |
| Oracle Financial Services Applications | ECM (Apache Log4j) | 8.0.8.2, 8.1.2.11 | 8.0.8.2 · 8.1.2.11 |
| Oracle Financial Services Applications | Infrastructure (Apache Log4j) | 14.5.0.0.0-14.9.0.0.0 | |
| Oracle Financial Services Applications | Third Party (Apache Log4j) | 8.0.8.1, 8.1.2.11 | 8.0.8.1 · 8.1.2.11 |
| Oracle Financial Services Applications | User Interface (Apache Log4j) | 8.0.8.0 | 8.0.8.0 |
| Oracle Fusion Middleware | Third Party Analysis Tool (Apache Log4j) | 12.2.1.4.0 | 12.2.1.4.0 |
| Oracle Hyperion | Installation/Configuration (Apache Log4j) | 11.2.25.0.000 | 11.2.25.0.0 |
| Oracle Retail Applications | Application Core (Apache Log4j) | 15.0, 16.0 | 15.0 · 16.0 |
| Oracle Retail Applications | NF Issuing (Apache Log4j) | 14.2 | 14.2 |
| Oracle Retail Applications | Operations & Maintenance (Apache Log4j) | 15.0, 16.0 | 15.0 · 16.0 |
| Oracle Siebel CRM | Siebel Approval Manager (Apache Log4j) | 17.0-26.8 | |
| Oracle Supply Chain | CAX Client (Apache Log4j) | 3.6 | 3.6 |
Maven packages
Affected and fixed versions, from OSV.dev| Package | Introduced | Fixed | Last affected |
|---|---|---|---|
org.apache.logging.log4j:log4j-core |
2.0-alpha1 | 2.25.4 |
unbounded |
org.apache.logging.log4j:log4j-core |
3.0.0-alpha1 | none | 3.0.0-beta3 |
Products and versions
2 products, 9 version entries| Source | Vendor | Product | Scheme | Affected versions |
|---|---|---|---|---|
| nvd | apache | log4j | generic | ≥ 2.0 and ＜ 2.25.4 · 3.0.0:alpha1 · 3.0.0:alpha1_rc1 · 3.0.0:alpha1_rc2 · 3.0.0:beta1 · 3.0.0:beta2 · 3.0.0:beta3 |
| osv | org.apache.logging.log4j | log4j-core | generic | ≥ 2.0 and ＜ 2.25.4 · ≥ 3.0.0 and ≤ 3.0.0 |
References
Timeline
Timeline
| Published | 2026-04-10 | By the CVE Program. |
|---|---|---|
| NVD record modified | 2026-10-26 | NVD's own last-modified date for this record. |