CVE-2026-105244
MEDIUMDescription
Improper Encoding or Escaping of Output vulnerability in the RemoteSyslogAppender of Apache log4net. Every character outside visible ASCII and space was removed from the record instead of being escaped, so non-ASCII text and control characters such as tabs disappeared without notice. A party whose data reaches a log message could make a distinct value look identical in the record, for example a user name holding a zero-width space logged as admin. Only applications that use RemoteSyslogAppender are affected. This issue affects Apache log4net: from 1.2.12 before 3.5.0. Users are recommended to upgrade to version 3.5.0, which fixes the issue.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Exploit Intelligence
Moderate risk: more likely to be exploited than 57% of all known CVEs.
References
Related Vulnerabilities
Other CWE-116 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2024-38475 | Critical | 9.1 | 100% | KEV | Fix |
| CVE-2022-36446 | Critical | 9.8 | 96% | - | Fix |
| CVE-2021-31806 | Medium | 6.5 | 95% | - | Fix |
| CVE-2022-30781 | High | 7.5 | 88% | - | Fix |
| CVE-2022-36099 | Critical | 9.9 | 76% | - | Fix |
| CVE-2022-36100 | Critical | 9.9 | 74% | - | Fix |
Common questions
How do I fix CVE-2026-105244?
Upgrade log4net to 3.5.0 or later.
Is CVE-2026-105244 being actively exploited?
Not that we know of. CVE-2026-105244 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.82% is the estimated probability that it will be exploited in the next 30 days. That is higher than 57% of all scored CVEs.
How severe is CVE-2026-105244?
CVE-2026-105244 has a CVSS v3 base score of 5.3, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-105244 affect?
Published advisories record a fix for log4net (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-10-09.