dbcve.org
TomcatWeb server / proxy · Apache

CVE-2016-8745

HIGH · 7.5 CVSS v3.0 Published 2017-08-10
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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 · unedited
A bug in the error handling of the send file code for the NIO HTTP connector in Apache Tomcat 9.0.0.M1 to 9.0.0.M13, 8.5.0 to 8.5.8, 8.0.0.RC1 to 8.0.39, 7.0.0 to 7.0.73 and 6.0.16 to 6.0.48 resulted in the current Processor object being added to the Processor cache multiple times. This in turn meant that the same Processor could be used for concurrent requests. Sharing a Processor can result in information leakage between requests including, not not limited to, session ID and the response body. The bug was first noticed in 8.5.x onwards where it appears the refactoring of the Connector code for 8.5.x onwards made it more likely that the bug was observed. Initially it was thought that the 8.5.x refactoring introduced the bug but further investigation has shown that the bug is present in all currently supported Tomcat versions.

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 confidence

A race condition in the error handling path of the NIO HTTP connector causes the same Processor object to be cached and reused for concurrent requests. This results in information leakage between requests, including session IDs and response bodies, due to shared processor state.

MitigationUpgrade to Tomcat 9.0.0.M14+, 8.5.9+, 8.0.40+, 7.0.74+, or 6.0.49+ to patch the faulty error handling in the NIO connector that causes Processor reuse.

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
Affected:= 7.0.0= 7.0.1= 7.0.2= 7.0.3= 7.0.4= 7.0.5= 7.0.6= 7.0.7= 7.0.8= 7.0.9= 7.0.11= 7.0.12

CVSS 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
High
Integrity
None
Availability
None

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify Tomcat installation location
    Locate the Tomcat installation directory (commonly /opt/tomcat, /usr/share/tomcat, or C:\Program Files\Apache Software Foundation\Tomcat on Windows)
    Affected if Tomcat 7.0.x is installed in any subdirectory
  2. Determine installed Tomcat version
    Check the VERSION file in the Tomcat lib directory, or inspect the jar file names in the lib folder for tomcat-catalina.jar which contains the version in its filename
    Affected if The version reads 7.0.0 through 7.0.12 inclusive
  3. Locate server.xml connector configuration
    Find the server.xml file in the Tomcat conf directory and examine the <Connector> elements
    Affected if A <Connector> element uses protocol="org.apache.coyote.http11.NioProtocol" or protocol="org.apache.coyote.http11.Nio2Protocol"
  4. Verify NIO connector is active
    Confirm the NIO or NIO2 connector in server.xml is not commented out and is the active connector handling HTTP requests
    Affected if An active NIO or NIO2 connector is configured and Tomcat is running with the vulnerable version

A user is affected if they are running Apache Tomcat 7.0.0-7.0.12 with an active NIO or NIO2 HTTP connector configuration.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to Tomcat 9.0.0.M14+, 8.5.9+, 8.0.40+, 7.0.74+, or 6.0.49+ to patch the faulty error handling in the NIO connector that causes Processor reuse.

Fix this in Tomcat Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA3.0 h
16.0 hours of engineering $2,760
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2016-8745 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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