CVE-2026-105239 (GCVE-0-2026-105239)
Vulnerability from cvelistv5 – Published: 2026-10-06 19:46 – Updated: 2026-10-06 19:58
VLAI
EPSS
VEX
Title
Apache log4net: NUL character truncates EventLogAppender records
Summary
Improper Neutralization of Null Byte or NUL Character vulnerability in the EventLogAppender of Apache log4net.
A NUL character in logged content ended the Windows Event Log record at that point, so everything the layout rendered after it, including exception text and trailing fields, was silently not stored. A party whose data reaches a log message could hide the rest of that record. Only applications on Windows that use EventLogAppender are affected.
This issue affects Apache log4net: from 1.2.9 before 3.5.0.
Users are recommended to upgrade to version 3.5.0, which fixes the issue.
Severity
5.3 (Medium)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-06 19:58 UTC
CWE
- CWE-158 - Improper Neutralization of Null Byte or NUL Character
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/apache/logging-log4net/pull/315 | patch |
| https://github.com/apache/logging-log4net/commit/… | patch |
| https://lists.apache.org/thread.html/9fx1qo5hc0tg… | vendor-advisory |
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Apache Software Foundation | Apache log4net |
Affected:
1.2.9 , < 3.5.0
(semver)
|
guessed | |
| Apache Software Foundation | Apache log4net |
Affected:
02e1e115435888485f2e28b414d267e39e799e07 , < dc5855a0720c91590fd7a81d729ea01fdd69e000
(git)
|
guessed |
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
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