TomcatWeb server / proxy · Apache
CVE-2023-45648
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedImproper 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceApache Tomcat versions 8.5.0-8.5.93, 9.0.0-9.0.81, 10.1.0-10.1.13, and 11.0.0-M11 contain an improper input validation flaw in HTTP trailer header parsing. When Tomcat sits behind a reverse proxy, a specially crafted invalid trailer header can cause Tomcat to misinterpret a single HTTP request as multiple requests, enabling request smuggling attacks.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
TomcatWeb server / proxy
>= 8.5.0, < 8.5.94>= 9.0.1, < 9.0.81>= 10.1.1, < 10.1.14= 9.0.0= 10.1.0= 11.0.0
Debian LinuxOperating system
= 10.0= 11.0= 12.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify installed Tomcat versionRun the Tomcat version command (version.sh or version.bat from the bin directory) or inspect the startup logs which display the version on launch. Alternatively, check the catalina.jar file properties for the version string.Affected if The installed version falls within 8.5.0-8.5.93, 9.0.0-9.0.81, 10.1.0-10.1.13, or 11.0.0-M11, including the specific versions 9.0.0, 10.1.0, and 11.0.0.
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Determine if Tomcat is deployed behind a reverse proxyReview server.xml for connector configurations that proxy to Tomcat (such as Apache HTTP Server, nginx, or other reverse proxies), or inspect network configuration and load balancer setups to see if external requests route through a proxy before reaching Tomcat.Affected if Tomcat is directly exposed to clients without a reverse proxy in front, the request smuggling attack as described does not apply, but the vulnerability still exists in the affected versions.
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Check if HTTP trailers are in useReview application configurations and logs for any HTTP traffic that uses trailer headers. Trailer headers are optional HTTP headers sent after the message body.Affected if HTTP trailer headers are being processed by this Tomcat instance.
You are affected if your Tomcat version is one of the affected versions listed AND the server receives HTTP requests through a reverse proxy that can send trailer headers to Tomcat.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped8.5.949.0.8110.1.14
Upgrade to Tomcat 8.5.94, 9.0.82, 10.1.14, or 11.0.0-M12 or later to patch the trailer header parsing vulnerability.
Tomcat 8.5.94+, 9.0.81+, 10.1.14+, or 11.0.0-M12+ (choose the major version matching your current installation)
- Identify the currently installed Tomcat version by checking the $CATALINA_HOME/lib/catalina.jar manifest or running 'catalina.sh version'
- Stop the Tomcat service before upgrading
- For Debian systems: run 'apt update && apt install tomcat*' to get the latest Debian-packaged version, or manually download the specific Tomcat version from https://tomcat.apache.org/
- If upgrading manually: download the binary zip/tar.gz for the appropriate version (8.5.94+, 9.0.81+, 10.1.14+, or 11.0.0-M12+) from https://tomcat.apache.org/download-80.cgi, https://tomcat.apache.org/download-90.cgi, or https://tomcat.apache.org/download-110.cgi
- Extract the new Tomcat version to the desired installation directory
- Copy the existing configuration files (server.xml, context.xml, web.xml) from the old installation to the new installation, reviewing for any deprecated settings
- Copy or update any custom libraries or applications deployed in the webapps directory
- Start the Tomcat service and verify the new version is running
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Tomcat
Scoped from the published advisory
- Consultation2.0 h
- Implementation3.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-45648 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2023-45648 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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