CVE-2023-46589VulnerabilityPublished 28 Nov 2023Updated 29 Oct 2025

CVE-2023-46589: Apache Tomcat · HTTP Request Smuggling

Affects Apache TomcatSource CVE Database V5

Not known to be exploited · CVSS 7.5 High · fixed in 11.0.0-M11 : patch Apache Tomcat soon.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 2.6% chance of exploitation in 30 days – higher than 85% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 11.0.0-M11, 10.1.16, 9.0.83 +1

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: High
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 28 Nov 2023
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade org.apache.tomcat/tomcat to 11.0.0-M11, 10.1.16, 9.0.83 or 8.5.96.

Affected software

Product	Affected	Fixed in
Mavenorg.apache.tomcat/tomcat`pkg:maven/org.apache.tomcat/tomcat`Other threats	Affected =11.0.0-M1 <11.0.0-M11 =10.1.0-M1 <10.1.16 =9.0.0-M1 <9.0.83 >=8.5.0 <8.5.96	Fixed in 11.0.0-M11 10.1.16 9.0.83 8.5.96

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

To mitigate CVE-2023-46589 effectively, European organizations should: 1) Immediately upgrade Apache Tomcat to the fixed versions: 8.5.96 or later, 9.0.83 or later, 10.1.16 or later, or 11.0.0-M11 or later. 2) Review and harden reverse proxy and load balancer configurations to detect and reject malformed or oversized HTTP headers, including trailer headers, to prevent request smuggling attempts. 3) Implement strict input validation and size limits on HTTP headers at the proxy level to complement Tomcat's protections. 4) Monitor web server and proxy logs for anomalies indicative of request smuggling, such as unexpected request splitting or unusual header patterns. 5) Conduct penetration testing and security assessments focusing on HTTP request smuggling vectors to identify residual risks. 6) Employ Web Application Firewalls (WAFs) with updated signatures capable of detecting HTTP request smuggling attacks. 7) Educate development and operations teams about the risks of HTTP request smuggling and the importance of timely patching and secure configuration. 8) For legacy or EOL Tomcat versions that cannot be immediately upgraded, consider isolating affected servers behind additional security layers or disabling HTTP trailer header support if feasible. These targeted actions go beyond generic patching advice and address the specific exploitation method and deployment context of this vulnerability.

Description

Improper Input Validation vulnerability in Apache Tomcat.Tomcat from 11.0.0-M1 through 11.0.0-M10, from 10.1.0-M1 through 10.1.15, from 9.0.0-M1 through 9.0.82 and from 8.5.0 through 8.5.95 did not correctly parse HTTP trailer headers. A trailer header that exceeded the header size limit could cause Tomcat to treat a single request as multiple requests leading to the possibility of request smuggling when behind a reverse proxy. Older, EOL versions may also be affected. Users are recommended to upgrade to version 11.0.0-M11 onwards, 10.1.16 onwards, 9.0.83 onwards or 8.5.96 onwards, which fix the issue.

Impact

For European organizations, the impact of CVE-2023-46589 can be significant, particularly for those relying on Apache Tomcat for hosting web applications, APIs, or internal services behind reverse proxies. Exploitation could allow attackers to bypass security controls such as web application firewalls, authentication mechanisms, or input validation filters by smuggling malicious requests. This can lead to unauthorized actions, data manipulation, or cache poisoning, undermining the integrity of web services. Critical sectors such as finance, healthcare, government, and telecommunications, which often deploy Tomcat in their infrastructure, may face increased risk of targeted attacks aiming to disrupt services or manipulate data. The vulnerability's network-based exploitation without authentication means attackers can attempt exploitation remotely, increasing the attack surface. Additionally, compromised request integrity can facilitate further attacks like session hijacking or privilege escalation. While no confidentiality breach is directly indicated, the indirect consequences of request smuggling can lead to sensitive information exposure or unauthorized access. The absence of known exploits in the wild provides a window for proactive mitigation, but the widespread use of Tomcat in Europe necessitates urgent patching to prevent potential exploitation.

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') (opens in a new tab)
Base weaknessOWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.
Implementation
Use a web server that employs a strict HTTP parsing procedure, such as Apache.
Implementation
Use only SSL communication.
Implementation
Terminate the client session after each request.
OWASP Cheat Sheets
REST Assessment (opens in a new tab)
REST Security (opens in a new tab)
Cross-Site Request Forgery Prevention (opens in a new tab)
Secure Design Principles (opens in a new tab)
OWASP ASVS 4.0.3
V13.2.5 (opens in a new tab)
Attack patterns
HTTP Response Smuggling (opens in a new tab)
HTTP Request Smuggling (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 29 Oct 2025, 12:26 UTC

WeaknessesCWE-444

Technical details

References

Community reviews

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