Jenkins: Unrestricted Upload of File with Dangerous Type
CVE-2023-43497 is a high-severity unrestricted upload of file with dangerous type vulnerability in Jenkins, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. The record lists versions 2.423, lts_2.414.1 as the first without the flaw, so updating Jenkins to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.97% chance of exploitation within 30 days, higher than 62% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Jenkins to 2.423 or lts_2.414.1, whichever matches your release line, or a later version.
- Read the advisory on jenkins.io for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Jenkins Project | Jenkins | before 2.423; before lts_2.414.1 | 2.423, lts_2.414.1 |
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
- LowA basic user account is enough.
- 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
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N. Scored by NVD.
Official description
In Jenkins 2.423 and earlier, LTS 2.414.1 and earlier, processing file uploads using the Stapler web framework creates temporary files in the default system temporary directory with the default permissions for newly created files, potentially allowing attackers with access to the Jenkins controller file system to read and write the files before they are used.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Unrestricted Upload of File with Dangerous Type
The product allows the upload or transfer of dangerous file types that are automatically processed within its environment.
How developers prevent this class of flaw
- Generate a new, unique filename for an uploaded file instead of using the user-supplied filename, so that no external input is used at all.
- When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
- Consider storing the uploaded files outside of the web document root entirely. Then, use other mechanisms to deliver the files dynamically.
More Unrestricted Upload of File with Dangerous Type vulnerabilities (CWE-434)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- openwall.com/lists/oss-security/2023/09/20/5Mailing List, Third Party Advisory
Other vulnerabilities in Jenkins
- 8.8 High severity
- 8.8 High severity
- 8.1 High severity
- 8.1 High severity
- 8.1 High severity
- 8.8 High severity
Recent Unrestricted Upload of File with Dangerous Type vulnerabilities
- 8.8 High severity
- 9.8 Critical severity
- 7.8 High severity
- 7.8 High severity
- 8.8 High severity
- 8.8 High severity
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