Apache log4net versions before 2.0.10 do not disable XML external entities when parsing log4net configuration files.
Apache log4net versions before 2.0.10 do not disable XML external entities when parsing log4net configuration files. This allows for XXE-based attacks in applications that accept attacker-controlled log4net configuration files.
- Published
- May 11, 2020
- Updated
- Jun 16, 2026
- EPSS
- 17.4% · 97th percentile
- CWE
- CWE-611
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Report tools
Action score
44
Plan
Add it to your regular patch cycle.
- CVSS
- 39 / 40 · 9.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 5 / 30 · 17.4%
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpAffected systems
| Vendor | Product | CPE |
|---|---|---|
| apache | log4net | cpe:2.3:a:apache:log4net |
| fedoraproject | fedora | cpe:2.3:o:fedoraproject:fedora |
| oracle | application testing suite | cpe:2.3:a:oracle:application_testing_suite |
| oracle | hospitality opera 5 | cpe:2.3:a:oracle:hospitality_opera_5 |
| oracle | hospitality simphony | cpe:2.3:a:oracle:hospitality_simphony |
| netapp | manageability software development kit | cpe:2.3:a:netapp:manageability_software_development_kit |
| netapp | snapcenter | cpe:2.3:a:netapp:snapcenter |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- apache log4netbefore 2.0.10
- fedoraproject fedora30
- fedoraproject fedora31
- fedoraproject fedora32
- netapp manageability software development kitall versions
- netapp snapcenterall versions
- oracle application testing suite13.3.0.1
- oracle hospitality opera 55.5
- oracle hospitality opera 55.6
- oracle hospitality simphony18.2.7.2
- oracle hospitality simphony19.1.3
Versions reported by the vendor
Affected version ranges reported by the assigning authority (apache). Independent of NVD's CPE analysis and usually ahead of it.
n/a Apache log4net
- Apache log4net up to 2.0.8affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:13 | log4net | before 1.2.10+dfsg-8 | 1.2.10+dfsg-8 |
| Debian:8 | log4net | before 1.2.10+dfsg-6+deb8u1 | 1.2.10+dfsg-6+deb8u1 |
| NuGet | log4net | before 2.0.10 | 2.0.10 |
| openSUSE:Tumbleweed | log4net | before 1.2.10-78.1 | 1.2.10-78.1 |
Same product
apache: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-40021Apache Log4net: Silent log event loss in XmlLayout and XmlLayoutSchemaLog4J due to unescaped XML 1.0 forbidden characters25Monitor
- CVE-2006-0743Format string vulnerability in LocalSyslogAppender in Apache log4net 1.2.9 might allow remote attackers to cause a denial of service (memory22Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:log4net | 1.2.10+dfsg-8 · Debian:13 | Package registry (OSV) |
| NuGet:log4net | 2.0.10 | Package registry (OSV) |
| opensuse:log4net | 1.2.10-78.1 · openSUSE:Tumbleweed | Package registry (OSV) |
Exploit status
Proof of concept available
A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.
Evidence
- Proof-of-concept repository on GitHub ×1
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Proof-of-concept repository on GitHub | stars:1 | 2021-12-31 |
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- Published
- First PoC+598 d
- TodayOct 9, 2026+2342 d
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
National notice (Türkiye Cybersecurity Directorate / USOM)
Official security notices citing this record; remediation advice is on the agency's page.
- TR-21-0331 · Apr 21, 2021(Oracle Güvenlik Uyarısı Yayınladı)
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-611 · Improper Restriction of XML External Entity ReferenceCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
—
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- issues.apache.org/jira/browse/LOG4NET-575
- lists.apache.org/thread.html/r00b16ac5e0bbf7009a0d167ed58f3f94d0033b0f4b3e3d5025cc4872%40%3Cdev.logging.apache.org%3E
- lists.apache.org/thread.html/r33564de316d4e4ba0fea1d4d079e62cde1ffe64369c1157243d840d9%40%3Cdev.logging.apache.org%3E
- lists.apache.org/thread.html/r525cbbd7db0aef4a114cf60de8439aa285decc34904d42a7f14f39c3%40%3Cdev.logging.apache.org%3E
- lists.apache.org/thread.html/r6543acafca3e2d24ff4b0c364a91540cb9378977ffa8d37a03ab4b0f%40%3Cdev.logging.apache.org%3E
- lists.apache.org/thread.html/r7ab6b6e702f11a6f77b0db2af2d5e5532f56ae4b99b5fe73c5200b6a%40%3Cdev.logging.apache.org%3E
- lists.apache.org/thread.html/r9de86a185575e6c5f92e2a70a1d2e2e9514dc4341251577aac8e3866%40%3Cdev.logging.apache.org%3E
- lists.apache.org/thread.html/rd2d72a017e238d1f345f9d14e075c81be16fc68a41c9e9ad9e29a732%40%3Cdev.logging.apache.org%3E
- lists.apache.org/thread.html/rdbac24c945ca5c69cd5348b5ac023bc625768f653335de146e09ae2d%40%3Cdev.logging.apache.org%3E
- lists.apache.org/thread.html/reab1c277c95310bad1038255e0757857b2fbe291411b4fa84552028a%40%3Cdev.logging.apache.org%3E
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/M2U233HVAQDSZ2PRG4XSGDASLY3J6ALH/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VKL2LPINAI6BCMXOH4V4HVHGLUXIWOFO/
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VT2DNNSW7C7FNK3MA3SLEUHGW5USYZKE/
- security.netapp.com/advisory/ntap-20220909-0001/
- www.oracle.com/security-alerts/cpuApr2021.html
- www.oracle.com/security-alerts/cpuapr2022.html
- www.oracle.com/security-alerts/cpujan2021.html
Vendor advisories and official records. Exploit/PoC links are deliberately left out.