CVE-2023-28709Network attack vector

Service interruption via off-by-one parameter counting

Published May 22, 2023 · Updated Feb 13, 2025

An off-by-one error in Apache Tomcat affected releases allows remote attackers to interrupt service through crafted multipart requests. Parameters.addParameter increments parameterCount before rejecting only values above maxParameterCount, so the exact boundary consumes the limit without blocking later uploaded parts. The flaw is reachable only with non-default HTTP connector settings that let query parameters reach maxParameterCount; excess request parts can exhaust server resources.

CVSS severity7.5
High
EPSS probability48.03%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

An off-by-one error in Apache Tomcat affected releases allows remote attackers to interrupt service through crafted multipart requests. Parameters.addParameter increments parameterCount before rejecting only values above maxParameterCount, so the exact boundary consumes the limit without blocking later uploaded parts. The flaw is reachable only with non-default HTTP connector settings that let query parameters reach maxParameterCount; excess request parts can exhaust server resources.

The record

CVE
CVE-2023-28709
Published
May 22, 2023
Updated
Feb 13, 2025
Vendor
The Apache Software Foundation
Product
Apache Tomcat
Classifications
CWE-193, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 22, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.1.5 <=10.1.7
  2. Affected versionversion=11.0.0-M2 <=11.0.0-M4
  3. Affected versionversion=8.5.85 <=8.5.87
  4. Affected versionversion=9.0.71 <=9.0.73

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Tomcatversion=10.1.5 <=10.1.7; version=11.0.0-M2 <=11.0.0-M4; version=8.5.85 <=8.5.87; version=9.0.71 <=9.0.73

Published CVSS scores

7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-193Off-by-one Error
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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