CVE-2023-26464: Apache Log4j 1.x (EOL) allows DoS in Chainsaw and SocketAppender
- Is it exploited?
Reported, not confirmed by CISA. VulnCheck KEV lists it as exploited in the wild. CISA has not added it to its Known Exploited Vulnerabilities catalog as of .
VulnCheck KEV lists it since . It cites 1 public report, the first from .
- How likely is exploitation in the next 30 days?
- 1.9%
EPSS score, percentile 79.7 of all scored records. A probability estimated by FIRST, not a report of exploitation.
- How severe?
- 7.5 High
CVSS v3.1 base score, from CISA's enrichment of the record
- What should I do?
CISA has set no required action, because the vulnerability is not in KEV.
- Which versions are affected?
Affected
- from 1.0.4 to before 2
Unaffected 2
Source: CISA KEV 2026.10.29, as of ; VulnCheck KEV, as of ; FIRST EPSS, as of ; CVE List, as of . About the data.
Description
Apache Log4j 1.x (EOL) allows DoS in Chainsaw and SocketAppender
** UNSUPPORTED WHEN ASSIGNED ** When using the Chainsaw or SocketAppender components with Log4j 1.x on JRE less than 1.7, an attacker that manages to cause a logging entry involving a specially-crafted (ie, deeply nested) hashmap or hashtable (depending on which logging component is in use) to be processed could exhaust the available memory in the virtual machine and achieve Denial of Service when the object is deserialized. This issue affects Apache Log4j before 2. Affected users are recommended to update to Log4j 2.x. NOTE: This vulnerability only affects products that are no longer supported by the maintainer.
Source: CVE List, as of . About the data.
What to do
Advisories and patches
This summary is based on the CVE record as of . Check the vendor's advisory before you act: affected versions and fixes can change.
Affected products and versions
Versions by product, as listed in the CVE record (1 product)
| Status | Versions |
|---|---|
| Affected | from 1.0.4 to before 2 |
| Unaffected | 2 |
Versions not listed are: unknown.
Versions the record lists as unaffected: 2.
Source: CVE List, as of . About the data.
Weakness
CWE-502
- CWE-502: Deserialization of Untrusted Data
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record.
Timeline
| Date | Event |
|---|---|
| CVE record published | |
| CVE record last updated |
References
1
Known exploited Apache vulnerabilities
- CVE-2016-3081: Apache Struts Command Injection Vulnerability
- CVE-2026-34486: Apache Tomcat Missing Encryption of Sensitive Data Vulnerability
- CVE-2026-34197: Apache ActiveMQ Improper Input Validation Vulnerability
- CVE-2024-38475: Apache HTTP Server Improper Escaping of Output Vulnerability
- CVE-2025-24813: Apache Tomcat Path Equivalence Vulnerability