GHSA-6v52-mj5r-7j2m CVE-2018-8037

Apache Tomcat Race Condition vulnerability

Medium Maven

Severity: 5.9 / 10; Medium · CVSS 3.0
Exploit chance (EPSS): 11.16%; Chance of exploitation in the next 30 days. Higher than 95.95% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Fix: 9.0.10; Upgrade org.apache.tomcat.embed:tomcat-embed-core to this version or later

Description

If an async request was completed by the application at the same time as the container triggered the async timeout, a race condition existed that could result in a user seeing a response intended for a different user. An additional issue was present in the NIO and NIO2 connectors that did not correctly track the closure of the connection when an async request was completed by the application and timed out by the container at the same time. This could also result in a user seeing a response intended for another user. Versions Affected: Apache Tomcat 9.0.0.M9 to 9.0.9 and 8.5.5 to 8.5.31.

Affected versions

Maven

Package	Vulnerable	Fixed in
org.apache.tomcat.embed:tomcat-embed-core	`>= 9.0.0.M9, < 9.0.10`	`9.0.10`
org.apache.tomcat.embed:tomcat-embed-core	`>= 8.5.5, < 8.5.32`	`8.5.32`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

org.apache.tomcat.embed:tomcat-embed-core Maven → `9.0.10`

maven

<dependency><groupId>org.apache.tomcat.embed</groupId><artifactId>tomcat-embed-core</artifactId><version>9.0.10</version></dependency>

gradle

implementation("org.apache.tomcat.embed:tomcat-embed-core:9.0.10")

Severity breakdown

CVSS 3.0 5.9

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

Attack vector: Network
Attack complexity: High
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Weakness

CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

How to prevent it

Architecture and Design: In languages that support it, use synchronization primitives. Only wrap these around critical code to minimize the impact on performance.
Architecture and Design: Use thread-safe capabilities such as the data access abstraction in Spring.
Architecture and Design: Minimize the usage of shared resources in order to remove as much complexity as possible from the control flow and to reduce the likelihood of unexpected conditions occurring. Additionally, this will minimize the amount of synchronization necessary and may even help to reduce the likelihood of a denial of service where an attacker may be able to repeatedly trigger a critical section (CWE-400).
Implementation: When using multithreading and operating on shared variables, only use thread-safe functions.
Implementation: Use atomic operations on shared variables. Be wary of innocent-looking constructs such as "x++". This may appear atomic at the code layer, but it is actually non-atomic at the instruction layer, since it involves a read, followed by a computation, followed by a write.
Implementation: Use a mutex if available, but be sure to avoid related weaknesses such as CWE-412.
Implementation: Avoid double-checked locking (CWE-609) and other implementation errors that arise when trying to avoid the overhead of synchronization.
Implementation: Disable interrupts or signals over critical parts of the code, but also make sure that the code does not go into a large or infinite loop.
Implementation: Use the volatile type modifier for critical variables to avoid unexpected compiler optimization or reordering. This does not necessarily solve the synchronization problem, but it can help.
Architecture and Design, Operation: Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.

References

Advisories

nvd.nist.gov/vuln/detail/CVE-2018-8037

Packages

github.com/apache/tomcat

Timeline

Oct 17, 2018 Published
Mar 11, 2024 Last updated by the source
Oct 31, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-83qj-6fr2-vhqg Apache Tomcat: Potential RCE and/or information disclosure and/or information corruption with partial PUT	Critical Known exploited	Also affects org.apache.tomcat.embed:tomcat-embed-core
GHSA-qppj-fm5r-hxr3 HTTP/2 Stream Cancellation Attack	Medium Known exploited	Also affects org.apache.tomcat.embed:tomcat-embed-core
GHSA-xjgh-84hx-56c5 Unrestricted Upload of File with Dangerous Type Apache Tomcat	High Known exploited	Also affects org.apache.tomcat.embed:tomcat-embed-core
CVE-2020-1938 Improper Privilege Management in Tomcat	Critical Known exploited	Also affects org.apache.tomcat.embed:tomcat-embed-core
GHSA-pjfr-qf3p-3q25 When running Apache Tomcat on Windows with HTTP PUTs enabled it was possible to upload a JSP file to the server	High Known exploited	Also affects org.apache.tomcat.embed:tomcat-embed-core
GHSA-h3x4-894j-xpx5 Apache Tomcat's FORM authentication process has an Incorrect Authorization vulnerability	Critical	Also affects org.apache.tomcat.embed:tomcat-embed-core
GHSA-9xv2-5v5q-p794 Apache Tomcat's DIGEST authenticator has an Authentication Bypass by Capture-replay vulnerability	Critical	Also affects org.apache.tomcat.embed:tomcat-embed-core
GHSA-f525-44xv-f2qj Apache Tomcat - HTTP/2 no-authority bypass of strict SNI validation	Critical	Also affects org.apache.tomcat.embed:tomcat-embed-core

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