# CVE-2026-62839: Microsoft SharePoint Server Spoofing Vulnerability

> An authorized attacker can exploit insufficiently protected credentials in Microsoft SharePoint to perform network spoofing, potentially exposing sensitive information.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 11 Aug 2026
- **Updated:** 28 Oct 2026
- **Also known as:** GHSA-59w3-vwvr-9367

## What is CVE-2026-62839?

CVE-2026-62839 is a medium-severity vulnerability in Microsoft Sharepoint Server, published on 11 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Insufficiently protected credentials in Microsoft Office SharePoint allows an authorized attacker to perform spoofing over a network.

Weakness: CWE-522 (Insufficiently Protected Credentials)

## Which versions are affected by CVE-2026-62839?

It affects 1 product.


Products: Microsoft Sharepoint Server.

## How do I fix CVE-2026-62839?

No fix has been published for CVE-2026-62839 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-62839 being exploited?

There is no known exploitation of CVE-2026-62839 in the wild and no public exploit code.

## Other vulnerabilities in Microsoft Sharepoint Server

- [CVE-2026-50522](https://insights.sbomify.com/CVE-2026-50522/): Microsoft SharePoint Deserialization of Untrusted Data Vulnerability (critical 9.8, exploited in the wild)
- [CVE-2026-58644](https://insights.sbomify.com/CVE-2026-58644/): Microsoft SharePoint Deserialization of Untrusted Data (critical 9.8, exploited in the wild)
- [CVE-2026-20963](https://insights.sbomify.com/CVE-2026-20963/): Microsoft SharePoint Deserialization of Untrusted Data (critical 9.8, exploited in the wild)
- [CVE-2025-53770](https://insights.sbomify.com/CVE-2025-53770/): Microsoft SharePoint Deserialization of Untrusted Data (critical 9.8, exploited in the wild)
- [CVE-2023-29357](https://insights.sbomify.com/CVE-2023-29357/): Microsoft SharePoint Server Privilege Escalation (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-62839 and fix it if it is affected.

What it is: CVE-2026-62839 is a medium-severity vulnerability in Microsoft Sharepoint Server, published on 11 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-62839 in the wild and no public exploit code.

Affected product: Microsoft Sharepoint Server. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-62839/ (Markdown: https://insights.sbomify.com/CVE-2026-62839/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-62839
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-62839
- OSV: https://osv.dev/vulnerability/CVE-2026-62839

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-62839/
Summaries are generated and may contain mistakes; the official description above is the record.