VulnerabilityPublished 10 Oct 2023Updated 29 Oct 2025

CVE-2023-45648: Apache Tomcat · Improper Input Validation

Affects Apache TomcatSource CVE Database V5

Exposed hosts seen by OffSeq Mirage · public detection template (Nuclei) · CVSS 5.3 Medium · fixed in 10.1.14 : update Apache Tomcat when convenient.

Data as of 26 Oct 2026, 09:15 UTC

CVSS 3.1 base score

5.3Medium

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

EPSS: 5.8% chance of exploitation in 30 days – higher than 93% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 10.1.14, 9.0.81, 8.5.94

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: Low
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: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on 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 10 Oct 2023
Detectable: evidence found.
nuclei template: Apache Tomcat - HTTP Request Smuggling
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: evidence found.
9 exposed hosts found; no attack traffic recorded

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

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 10.1.14, 9.0.81 or 8.5.94.

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-M12 =10.1.0-M1 <10.1.14 =9.0.0-M1 <9.0.81 =8.5.0 <8.5.94	Fixed in 10.1.14 9.0.81 8.5.94

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

AI-suggested

European organizations should prioritize upgrading Apache Tomcat to the fixed versions: 8.5.94 or later, 9.0.81 or later, 10.1.14 or later, or 11.0.0-M12 or later. Where immediate upgrade is not feasible, organizations should implement strict input validation and filtering at the reverse proxy or web application firewall level to detect and block malformed HTTP trailer headers. Reviewing and hardening reverse proxy configurations to ensure consistent HTTP parsing behavior between front-end and backend servers can reduce risk. Monitoring HTTP traffic for anomalies indicative of request smuggling attempts is advised. Additionally, organizations should audit their infrastructure to identify all Tomcat instances, including legacy and development environments, to ensure comprehensive patching. Employing layered security controls such as network segmentation and strict access controls around Tomcat servers can limit potential impact. Finally, maintaining up-to-date threat intelligence feeds and monitoring vendor advisories will help detect emerging exploit attempts.

Description

Improper Input Validation vulnerability in Apache Tomcat.Tomcat from 11.0.0-M1 through 11.0.0-M11, from 10.1.0-M1 through 10.1.13, from 9.0.0-M1 through 9.0.81 and from 8.5.0 through 8.5.93 did not correctly parse HTTP trailer headers. A specially crafted, invalid trailer header 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-M12 onwards, 10.1.14 onwards, 9.0.81 onwards or 8.5.94 onwards, which fix the issue.

Impact

For European organizations, this vulnerability could lead to HTTP request smuggling attacks that undermine the integrity of web applications hosted on Apache Tomcat servers. Attackers could exploit this to bypass security controls such as web application firewalls or authentication mechanisms, potentially allowing unauthorized actions or data manipulation. While confidentiality and availability impacts are limited, the integrity of HTTP request processing is compromised, which could facilitate further attacks like session hijacking, cache poisoning, or cross-site scripting. Organizations relying on Tomcat behind reverse proxies or load balancers are particularly at risk. Given the widespread use of Apache Tomcat in European enterprises, government agencies, and critical infrastructure, exploitation could disrupt services or expose sensitive internal operations. The medium CVSS score reflects moderate risk, but the ease of remote exploitation without authentication increases urgency for patching. The absence of known exploits in the wild currently reduces immediate threat but does not eliminate future risk.

CWE-20Improper Input Validation (opens in a new tab)
Class weaknessLikelihood of exploit: HighCWE Top 25 (2025): #18OWASP Top 10 A05:2025: Injection (opens in a new tab)
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
Architecture and Design · Attack Surface Reduction
Consider using language-theoretic security (LangSec) techniques that characterize inputs using a formal language and build "recognizers" for that language. This effectively requires parsing to be a distinct layer that effectively enforces a boundary between raw input and internal data representations, instead of…
Architecture and Design · Libraries or Frameworks
Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
Architecture and Design · Implementation · Attack Surface Reduction
Understand all the potential areas where untrusted inputs can enter the product, including but not limited to: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any…
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
Injection Prevention (opens in a new tab)
SQL Injection Prevention (opens in a new tab)
Injection Prevention in Java (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Buffer Overflow via Environment Variables (opens in a new tab)
Server Side Include (SSI) Injection (opens in a new tab)
Cross Zone Scripting (opens in a new tab)
Command Line Execution through SQL Injection (opens in a new tab)
Object Relational Mapping Injection (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 29 Oct 2025, 12:22 UTC

Public exploits and detectiona Nuclei detection template

WeaknessesCWE-20

Technical details

References

Community reviews

Related threats