Apache Tomcat: Time-of-check Time-of-use (TOCTOU) Race Condition
CVE-2024-56337 is a critical-severity time-of-check time-of-use (TOCTOU) race condition vulnerability in Apache Tomcat from Apache, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Apache Tomcat versions: 11.0.0-M1 through 11.0.1; 10.1.0-M1 through 10.1.33; 9.0.0.M1 through 9.0.97, and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 8.97% chance of exploitation within 30 days, which is in the top 4.66% of all scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Tomcat to 9.0.98 or 10.1.34 or 11.0.2, whichever matches your release line, or a later version.
- Read the advisory on lists.apache.org for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Apache | Apache Tomcat | 11.0.0-M1 through 11.0.1; 10.1.0-M1 through 10.1.33; 9.0.0.M1 through 9.0.97; 8.5.0 through 8.5.100 | Not stated |
| Apache | Tomcat | 9.0.0 up to, but not including, 9.0.98; 10.1.0 up to, but not including, 10.1.34; 11.0.0 up to, but not including, 11.0.2 | 9.0.98, 10.1.34, 11.0.2 |
| NetApp | Bootstrap OS | Not specified in the record | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CISA (ADP).
Official description
Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability in Apache Tomcat. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.1, from 10.1.0-M1 through 10.1.33, from 9.0.0.M1 through 9.0.97. The following versions were EOL at the time the CVE was created but are known to be affected: 8.5.0 though 8.5.100. Other, older, EOL versions may also be affected. The mitigation for CVE-2024-50379 was incomplete. Users running Tomcat on a case insensitive file system with the default servlet write enabled (readonly initialisation parameter set to the non-default value of false) may need additional configuration to fully mitigate CVE-2024-50379 depending on which version of Java they are using with Tomcat: - running on Java 8 or Java 11: the system property sun.io.useCanonCaches must be explicitly set to false (it defaults to true) - running on Java 17: the system property sun.io.useCanonCaches, if set, must be set to false (it defaults to false) - running on Java 21 onwards: no further configuration is required (the system property and the problematic cache have been removed) Tomcat 11.0.3, 10.1.35 and 9.0.99 onwards will include checks that sun.io.useCanonCaches is set appropriately before allowing the default servlet to be write enabled on a case insensitive file system. Tomcat will also set sun.io.useCanonCaches to false by default where it can.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Time-of-check Time-of-use (TOCTOU) Race Condition
The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.
How developers prevent this class of flaw
- The most basic advice for TOCTOU vulnerabilities is to not perform a check before the use. This does not resolve the underlying issue of the execution of a function on a resource whose state and identity cannot be assured, but it does help to limit the false sense of security given by the check.
- When the file being altered is owned by the current user and group, set the effective gid and uid to that of the current user and group when executing this statement.
- Limit the interleaving of operations on files from multiple processes.
More Time-of-check Time-of-use (TOCTOU) Race Condition vulnerabilities (CWE-367)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Third-party and government advisories
- cve.org/CVERecord?id=CVE-2024-50379Third Party Advisory
- security.netapp.com/advisory/ntap-20250103-0002/Third Party Advisory
Other references
Other vulnerabilities in Apache Tomcat
- 7.5 High severity
- 7.5 High severity
- 8.1 High severity
- 9.1 Critical severity
- 9.1 Critical severity
- 8.1 High severity
Recent Time-of-check Time-of-use (TOCTOU) Race Condition vulnerabilities
- 9.8 Critical severity
- 7.3 High severity
- 7.0 High severity
- 8.1 High severity
- 7.2 High severity
- 7.0 High severity
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