Pro Cloud Server: Concurrent Execution using Shared Resource with Improper Synchronization
CVE-2026-42099 is a high-severity concurrent execution using shared resource with improper synchronization vulnerability in Pro Cloud Server from Sparx Systems, with a CVSS 3.1 base score of 7.5 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. Affected Pro Cloud Server versions: 6.1 and earlier. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.72% chance of exploitation within 30 days, higher than 55% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of Pro Cloud Server you run against the affected versions below, and install the vendor's latest release.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Sparx Systems | Pro Cloud Server | 6.1 and earlier | 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
- HighSuccess depends on conditions outside the attacker's control.
- 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
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 7.7 | High | CNA (cert.pl) |
| CVSS 3.1 | 7.5 | High | NVD |
Official description
Sparx Pro Cloud Server is vulnerable to a Race Condition in the /data_api/dl_internal_artifact.php endpoint. The application downloads the properties of the object pointed by guid parameter and saves loaded content in current location (__DIR__) under the specified name. An attacker with repository access can control both the filename and file contents, allowing the creation of a malicious PHP file in a current directory. Although the file is deleted after processing, a race condition exists: if the response transmission is delayed (e.g., via a large file or slow client connection), the file remains accessible. During this window, the attacker can issue a second request to execute the malicious PHP file, resulting in remote code execution. The vendor was notified early about this vulnerability, but didn't respond with the details of vulnerability or vulnerable version range. Only version 6.1 (build 167) and below were tested and confirmed as vulnerable, other versions were not tested and might also be vulnerable.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Concurrent Execution using Shared Resource with Improper Synchronization
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 developers prevent this class of flaw
- In languages that support it, use synchronization primitives. Only wrap these around critical code to minimize the impact on performance.
- Use thread-safe capabilities such as the data access abstraction in Spring.
- 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).
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
- cert.pl/en/posts/2026/05/CVE-2026-42096Third Party Advisory
- efigo.pl/blog/CVE-2026-42096/Third Party Advisory
Technical write-ups (may include proof of concept)
- sploit.tech/2026/05/19/Sparx-Enterprise-Architect-PCS.htmlExploit, Third Party Advisory
Other references
Other vulnerabilities in Pro Cloud Server
- 7.5 High severity
- 8.8 High severity
- 8.8 High severity
- 8.3 High severity
Recent Concurrent Execution using Shared Resource with Improper Synchronization vulnerabilities
- 7.8 High severity
- 8.3 High severity
- 7.5 High severity
- 7.0 High severity
- 7.0 High severity
- 7.0 High severity
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