CVE-2016-8745 — tomcat-util
HIGHCVE-2016-8745 is a high-severity (CVSS 7.5) CWE-388 vulnerability in org.apache.tomcat:tomcat-util. EPSS puts its 30-day exploitation probability at 16.0% (97th percentile). A fix is available for org.apache.tomcat:tomcat-util — see the affected versions and patch details below.
Concurrent Execution using Shared Resource with Improper Synchronization in Apache Tomcat
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2016-8745.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2016-8745 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the 10–50% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
org.apache.tomcat:tomcat-util☕org.apache.tomcat:tomcat-util☕org.apache.tomcat:tomcat-util☕org.apache.tomcat:tomcat-util☕org.apache.tomcat:tomcat-utilReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.apache.tomcat:tomcat-util | ≥ 9.0.0.M1&&< 9.0.0.M14 | 9.0.0.M14org.apache.tomcat:tomcat-util:9.0.0.M14 |
| ☕Maven | org.apache.tomcat:tomcat-util | ≥ 8.5.0&&< 8.5.9 | 8.5.9org.apache.tomcat:tomcat-util:8.5.9 |
| ☕Maven | org.apache.tomcat:tomcat-util | ≥ 8.0.0-RC1&&< 8.0.41 | 8.0.41org.apache.tomcat:tomcat-util:8.0.41 |
| ☕Maven | org.apache.tomcat:tomcat-util | ≥ 7.0.0&&< 7.0.75 | 7.0.75org.apache.tomcat:tomcat-util:7.0.75 |
| ☕Maven | org.apache.tomcat:tomcat-util | ≥ 6.0.16&&< 6.0.50 | 6.0.50org.apache.tomcat:tomcat-util:6.0.50 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.tomcat:tomcat-util, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.apache.tomcat:tomcat-util to 9.0.0.M14 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2016-8745 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2016-8745 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2016-8745. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 6 | tomcat6-0:6.0.24-105.el6_8 | RHSA-2017:0527 |
| Red Hat Enterprise Linux 7 | tomcat-0:7.0.69-11.el7_3 | RHSA-2017:0935 |
| Red Hat JBoss Web Server 3.1 | see advisory | RHSA-2017:0457 |
| Red Hat JBoss Web Server 3 for RHEL 6 | hibernate4-eap6-0:4.2.23-1.Final_redhat_1.1.ep6.el6 | RHSA-2017:0455 |
| Red Hat JBoss Web Server 3 for RHEL 7 | hibernate4-eap6-0:4.2.23-1.Final_redhat_1.1.ep6.el7 | RHSA-2017:0456 |
Frequently Asked Questions
Is CVE-2016-8745 in your dependencies?
O3 Security finds CVE-2016-8745 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.