CVE-2017-9791: in the CISA KEV catalogue
Apache Struts 1 Improper Input Validation Vulnerability. CISA added CVE-2017-9791 to the Known Exploited Vulnerabilities catalogue on 2022-02-10 with a default due date of 2022-08-10. Known ransomware campaign use: Unknown. Forensic triage flag: No.
The Struts 1 plugin in Apache Struts might allow remote code execution via a malicious field value passed in a raw message to the ActionMessage. (CISA description)
- Vendor / product
- Apache Struts 1
- CWE
- CWE-20
- CISA required action
- Apply updates per vendor instructions.
- EPSS
- 99%, percentile 99 (scored 2026-11-03)
EPSS puts about 99 in 100 odds (99%) on exploitation activity being observed in the next 30 days. Its score is higher than or equal to that of 99% of scored CVEs. This is a model estimate about exploitation anywhere, not about your environment.
Vendor and reference links (from CISA)
Your own deadline under CISA BOD 26-04 depends on exposure, automatability and technical impact: work it out with the BOD 26-04 calculator.
Frequently asked questions
Is CVE-2017-9791 in the CISA KEV catalogue?
Yes. CISA added CVE-2017-9791 (Apache Struts 1 Improper Input Validation Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2022-02-10. CISA's default due date for it is 2022-08-10.
Is CVE-2017-9791 used in ransomware attacks?
CISA marks known ransomware campaign use as Unknown for CVE-2017-9791. That means CISA lacks confirmation, not that ransomware groups do not use it.
What should I do about CVE-2017-9791?
CISA's required action: Apply updates per vendor instructions.
Sources
- CISA, Known Exploited Vulnerabilities Catalog (accessed 2026-11-03)
- FIRST, Exploit Prediction Scoring System (EPSS) (EPSS by FIRST; scores generated by Empirical Security)
- NVD record for CVE-2017-9791