# CVE-2026-90870: Progress WS_FTP Server resource exhaustion in Ad Hoc Transfer

Source: https://junglewise.ai/threats/cve-2026-90870-a-missing-release-of-backend-receiver-sessions-in-the-ad-hoc  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-29. Updated: 2026-10-29  
License: CC BY 4.0 with a link back

CVE-2026-90870 · Severity: medium · CVSS 5.3 · Published 2026-10-29

Progress WS_FTP Server is a file transfer solution that handles FTP connections for enterprises. A flaw in its Ad Hoc Transfer component fails to properly release backend receiver sessions, allowing attackers to exhaust server resources and degrade or disable the service. This affects Windows systems running versions before 2024.0.7 and 2025.0.4.

Technologies: [Progress Software WS FTP Server](https://junglewise.ai/threats/technologies/progress-software-ws-ftp-server). Vendors: [Progress Software](https://junglewise.ai/threats/vendors/progress-software).

## Quick answers

**Is CVE-2026-90870 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-90870 being exploited in the wild.

**How severe is CVE-2026-90870?** Medium severity, with a CVSS score of 5.3, published 29 October 2026.

**Which products and versions are affected?** Progress Software WS FTP Server prior to 2024.0.7 and 2025.0.4.

**Is there a fix for CVE-2026-90870?** Yes: fixed in 2024.0.7, 2025.0.4. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-90870 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-90870?** Check whether you run Progress Software WS FTP Server at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 2024.0.7, 2025.0.4

## Technical details

The Ad Hoc Transfer component in WS_FTP Server does not properly release backend receiver sessions, leading to resource exhaustion. The vulnerability can be exploited remotely over the network and results in server resource exhaustion and service degradation. Patched versions 2024.0.7 and 2025.0.4 address this issue.

## Affected products

- Progress Software WS_FTP Server prior to 2024.0.7 and 2025.0.4

## Timeline

- 2026-10-29: disclosed

## References

- [https://progress.lightning.force.com/lightning/r/Knowledge__kav/ka7Pb000001vl86IAA/view](https://progress.lightning.force.com/lightning/r/Knowledge__kav/ka7Pb000001vl86IAA/view)

## Related threats

- [Progress Software WS_FTP Server access restriction bypass in Thin Client Web Transfer](https://junglewise.ai/threats/cve-2026-115341-improper-access-restrictions-in-the-thin-client-web-transfer)
- [Progress Software WS_FTP Server sensitive data exposure in temp file](https://junglewise.ai/threats/cve-2026-115340-progress-software-ws-ftp-server-versions-prior-to-2025-0-5-on)
- [Progress Software WS_FTP Server denial of service via insufficient resource limits](https://junglewise.ai/threats/cve-2026-115339-insufficient-resource-limits-in-progress-software-ws-ftp-server)
- [Progress WS_FTP Server incorrect quota accounting](https://junglewise.ai/threats/cve-2026-115336-incorrect-quota-accounting-in-progress-software-ws-ftp-server)
- [Progress Software WS_FTP Server code injection in Manager web console](https://junglewise.ai/threats/cve-2026-90872-improper-neutralization-of-directives-in-dynamically-evaluated)