VulnTideExploited vulnerabilities, by vendor. Data as of 28 Oct 2026.
Known exploitedIn CISA's KEV catalog since 10 February 2022Ransomware use: unknown
Apache Struts 1

CVE-2017-9791: Apache Struts 1 Improper Input Validation Vulnerability

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 10 Feb 2022, 1,676 days after the CVE record was published.

How likely is exploitation in the next 30 days?
98.9%

EPSS score, percentile 99.9 of all scored records

How severe?
9.8 Critical

CVSS v3.1 base score, from CISA's enrichment of the record

What should I do?

CISA deadline 10 Aug 2022. Apply updates per vendor instructions.

The CVE record links no vendor advisory, patch or mitigation.

Which versions are affected?

Affected

  • 2.1.x series
  • 2.3.x series

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

What to do

Required action, set by CISA

Apply updates per vendor instructions.

CISA due date for this action: 10 August 2022.

Advisories and patches

The CVE record links no vendor advisory, patch or mitigation.

Linked from CISA's catalog entry

Affected products and versions

As listed in the CVE record.

Apache Software Foundation Apache Struts
StatusVersions
Affected2.1.x series
Affected2.3.x series

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

About this vulnerability

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.

Summary: CISA's KEV catalog, as of 28 Oct 2026.

  • CISA added CVE-2017-9791 to its Known Exploited Vulnerabilities (KEV) catalog on 10 Feb 2022.
  • CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
  • The due date CISA sets for the required action is 10 Aug 2022.
  • The CVE record was published on 10 Jul 2017, 1,676 days before it was added to KEV.
  • The CVE record carries a CVSS v3.1 base score of 9.8 (Critical), taken from CISA's enrichment of the record.
  • FIRST's EPSS model puts the probability of exploitation in the next 30 days at 98.9% (percentile 99.9), as of 28 Oct 2026.
  • CISA's SSVC assessment in the CVE record: exploitation active, automatable yes, technical impact total.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.

Description

The Struts 1 plugin in Apache Struts 2.1.x and 2.3.x might allow remote code execution via a malicious field value passed in a raw message to the ActionMessage.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

Weakness

  • CWE-20: Improper Input Validation

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

DateEvent
10 Jul 2017CVE record published
10 Feb 2022Added to CISA KEV
10 Aug 2022CISA due date for the required action
21 Oct 2025CVE record last updated

References

More exploited Apache vulnerabilities

  • CVE-2016-3081: Apache Struts Command Injection Vulnerability (added 8 Oct 2026)
  • CVE-2026-34486: Apache Tomcat Missing Encryption of Sensitive Data Vulnerability (added 4 Aug 2026)
  • CVE-2026-34197: Apache ActiveMQ Improper Input Validation Vulnerability (added 16 Apr 2026)
  • CVE-2024-38475: Apache HTTP Server Improper Escaping of Output Vulnerability (added 1 May 2025)
  • CVE-2025-24813: Apache Tomcat Path Equivalence Vulnerability (added 1 Apr 2025)
  • CVE-2024-45195: Apache OFBiz Forced Browsing Vulnerability (added 4 Feb 2025)