CVE-2020-9493 — Java deserialization in Chainsaw

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

1. Identify exposed assets running the affected vendor/product/version combinations (Apache Software Foundation Chainsaw, Apache Software Foundation Log4j, Qos Reload4j).
2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
3. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
4. EPSS ahead of 92% of scored CVEs: prioritize it in the patch queue.
5. Search available logs for exploit probes matching the vulnerability class (insecure deserialization), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-502 · Deserialization of Untrusted Data

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 15, 2026 · 3 reading(s) · max 4.61%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

• Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
• Monitor serialized objects in requests and unexpected processes spawned by the runtime.

Timeline

What happened to this CVE, newest first.

• 2026
• Affected products added · apache software foundation/apache chainsaw
  Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
• SSVC assessment updated
  Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
• Record published
  Oct 13, 2026
• CVSS changed · 9.8
  Oct 13, 2026 · NIST National Vulnerability Database
• Source status changed · → Modified
  Oct 13, 2026 · NIST National Vulnerability Database
• Record created in this database
  Oct 13, 2026 · NIST National Vulnerability Database
• 2021
• CVE published
  Jun 16, 2021 · apache

Source activity

Repeated readings are counted rather than listed.

• 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

4 on the record

• www.openwall.com/lists/oss-security/2021/06/16/1
  Mailing List, Tool Signature, x_refsource_MISC, NIST National Vulnerability Database
• www.openwall.com/lists/oss-security/2021/06/16/1
  Mailing List, Third Party Advisory, mailing-list, x_refsource_MLIST, NIST National Vulnerability Database
• www.openwall.com/lists/oss-security/2022/01/18/5
  Mailing List, Third Party Advisory, mailing-list, x_refsource_MLIST, NIST National Vulnerability Database
• lists.apache.org/thread.html/r50d389c613ba6062a26aa57e163c09bfee4ff2d95d67331d75265b83
  mailing-list, x_refsource_MLIST, NIST National Vulnerability Database

Elsewhere on this site

Related CVEs (same products)

• Medium CVE-2026-49844 Apache Log4j API: Improper serialization of non-finite floating-point values in MapMessage.asJson() Jul 10, 2026
• High CVE-2026-34478 Apache Log4j Core: Log injection in Rfc5424Layout due to silent configuration incompatibility Apr 10, 2026
• High CVE-2026-34479 Apache Log4j 1 to Log4j 2 bridge: Silent log event loss in Log4j1XmlLayout due to unescaped XML 1.0 forbidden characters Apr 10, 2026
• High CVE-2026-34480 Apache Log4j Core: Silent log event loss in XmlLayout due to unescaped XML 1.0 forbidden characters Apr 10, 2026
• High CVE-2026-34481 Apache Log4j JSON Template Layout: Improper serialization of non-finite floating-point values in JsonTemplateLayout Apr 10, 2026
• Medium CVE-2026-34477 Apache Log4j Core: verifyHostName attribute silently ignored in TLS configuration, allowing hostname verification bypass Apr 10, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

• No fixed version, patch or mitigation documented.
• No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
• No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
• No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2020-9493 is "Java deserialization in Chainsaw", rated Critical. It affects Chainsaw (Apache Software Foundation); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.8 describes technical severity. EPSS 4.61% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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