# CVE-2026-81858: IBM i out-of-bounds read in File Server

Source: https://junglewise.ai/threats/cve-2026-81858-ibm-i-7-3-7-4-7-5-and-7-6-could-allow-a-remote-authenticated  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-13. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-81858 · Severity: medium · CVSS 5.4 · Published 2026-10-13

IBM i is an enterprise operating system that runs business-critical applications and file services on IBM Power Systems. A flaw in the File Server component allows authenticated attackers to crash the system (denial of service) or read sensitive information from memory. This could disrupt business operations or expose confidential data.

Technologies: [IBM I](https://junglewise.ai/threats/technologies/i), [IBM I 7.3](https://junglewise.ai/threats/technologies/i-7-3), [IBM I 7.4](https://junglewise.ai/threats/technologies/i-7-4), [IBM I 7.5](https://junglewise.ai/threats/technologies/i-7-5), [IBM I 7.6](https://junglewise.ai/threats/technologies/i-7-6). Vendors: [IBM](https://junglewise.ai/threats/vendors/ibm).

## Quick answers

**Is CVE-2026-81858 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-81858 being exploited in the wild.

**How severe is CVE-2026-81858?** Medium severity, with a CVSS score of 5.4, published 13 October 2026.

**Which products and versions are affected?** IBM I 7.3 7.3; IBM I 7.4 7.4; IBM I 7.5 7.5; IBM I 7.6 7.6.

**Is there a fix for CVE-2026-81858?** Yes: fixed in IBM i 7.3 PTF SJ11619, 7.4 PTF SJ11620, 7.5 PTF SJ11621, 7.6 PTF SJ11622. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-81858 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2026-81858?** Check whether you run IBM I, IBM I 7.3, IBM I 7.4 or one of the others listed 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 IBM i 7.3 PTF SJ11619, 7.4 PTF SJ11620, 7.5 PTF SJ11621, 7.6 PTF SJ11622

## Technical details

An out-of-bounds read vulnerability in IBM i's File Server allows a remote authenticated attacker to trigger a denial of service condition and obtain information. The vulnerability is accessible over the network and requires valid credentials; no user interaction is needed. Patched versions are available via PTF releases for all affected versions.

## Affected products

- IBM i 7.3 7.3
- IBM i 7.4 7.4
- IBM i 7.5 7.5
- IBM i 7.6 7.6

## Timeline

- 2026-09-30: disclosed

## References

- [https://www.ibm.com/support/pages/node/7290195](https://www.ibm.com/support/pages/node/7290195)

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- [IBM i NFS version restriction bypass](https://junglewise.ai/threats/cve-2026-17068-ibm-i-7-3-7-4-7-5-and-7-6-could-allow-a-local-attacker-to-bypass)