# CVE-2026-18633: Synology DiskStation Manager uninitialized pointer access in nfsd

Source: https://junglewise.ai/threats/cve-2026-18633-an-access-of-uninitialized-pointer-vulnerability-in-the-nfsd-in  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-12. Updated: 2026-11-12  
License: CC BY 4.0 with a link back

CVE-2026-18633 · Severity: high · CVSS 7.5 · Published 2026-11-12

Synology DiskStation Manager (DSM) is a network-attached storage operating system that manages data backup, file sharing, and media services. A flaw in the NFS file sharing service allows remote attackers to crash the system without needing any authentication, causing service outages and disrupting access to stored data.

Technologies: [Synology DiskStation Manager (DSM)](https://junglewise.ai/threats/technologies/diskstation-manager-dsm). Vendors: [Synology](https://junglewise.ai/threats/vendors/synology).

## Quick answers

**Is CVE-2026-18633 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-18633 being exploited in the wild.

**How severe is CVE-2026-18633?** High severity, with a CVSS score of 7.5, published 12 November 2026.

**Which products and versions are affected?** Synology DiskStation Manager (DSM) 7.3.x before 7.3.2-86009-5, 7.4.x before 7.4.1-90080-1.

**Is there a fix for CVE-2026-18633?** Yes: fixed in DSM 7.3.2-86009-5, 7.4.1-90080-1 or above. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-18633 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-18633?** Check whether you run Synology DiskStation Manager (DSM) 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 DSM 7.3.2-86009-5, 7.4.1-90080-1 or above

## Technical details

An uninitialized pointer dereference vulnerability (CWE-824) in the nfsd component allows remote, unauthenticated attackers to trigger a denial-of-service condition via malformed NFS requests. The vulnerability requires only network access with no authentication or user interaction. A successful exploit crashes the NFS service, disrupting file access.

## Affected products

- Synology DiskStation Manager (DSM) 7.3.x before 7.3.2-86009-5, 7.4.x before 7.4.1-90080-1

## Timeline

- 2026-11-10: disclosed
- 2026-11-10: advisory

## References

- [https://www.synology.com/en-global/security/advisory/Synology_SA_26_18](https://www.synology.com/en-global/security/advisory/Synology_SA_26_18)

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