What is CVE-2023-28709?

CVE-2023-28709 is a high-severity vulnerability in Apache Tomcat, classified under Off-by-one Error. CVSS score: 7.5/10. Published 2023-05-22.

How severe is CVE-2023-28709?

High severity. CVSS v3 base score is 7.5 out of 10.

Is CVE-2023-28709 known to be exploited?

2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Apache Tomcat

CVE-2023-28709

The fix for CVE-2023-24998 was incomplete for Apache Tomcat 11.0.0-M2 to 11.0.0-M4, 10.1.5 to 10.1.7, 9.0.71 to 9.0.73 and 8.5.85 to 8.5.87. If non-default HTTP connector settings were used such that the maxParameterCount could be reached using query string parameters and a request was submitted that supplied exactly maxParameterCount parameters in the query string, the limit for uploaded request parts could be bypassed with the potential for a denial of service to occur.

Published 2023-05-22 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.480 (98.8th percentile), scored 2026-09-27.

Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 99th percentile — 98.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.499 · newest: 0.480 · change: -0.019

Affected products

Apache Tomcat — versions 11.0.0
Apache Software Foundation Tomcat — versions 11.0.0-M2, 10.1.5, 9.0.71
NetApp 7-Mode Transition Tool
Debian Linux — versions 12.0

Weakness classification (CWE)

CWE-193 — Off-by-one Error

Public proof-of-concept exploits

References

lists.apache.org/thread/7wvxonzwb7k9hx9jt3q33cmy7j97jo3j (vendor-advisory, Mailing List, Vendor Advisory)
www.openwall.com/lists/oss-security/2023/05/22/1 (Mailing List, Third Party Advisory)
security.gentoo.org/glsa/202305-37 (Third Party Advisory)
security.netapp.com/advisory/ntap-20230616-0004/ (Third Party Advisory)
www.debian.org/security/2023/dsa-5521 (Third Party Advisory)

Frequently asked questions

What is CVE-2023-28709?: CVE-2023-28709 is a high-severity vulnerability in Apache Tomcat, classified under Off-by-one Error. CVSS score: 7.5/10. Published 2023-05-22.
How severe is CVE-2023-28709?: High severity. CVSS v3 base score is 7.5 out of 10.
Is CVE-2023-28709 known to be exploited?: 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.