# CVE-2026-105959: Spice-server: spice: heap buffer overflow via glz dictionary max_encoders integer truncation

> A malicious authenticated SPICE client can trigger a heap buffer overflow via integer truncation during VM live migration, potentially leading to code execution or denial of service.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Oct 2026
- **Updated:** 20 Oct 2026
- **Also known as:** BELL-CVE-2026-105959, DEBIAN-CVE-2026-105959, GHSA-m5f2-676c-jfj7, UBUNTU-CVE-2026-105959

## What is CVE-2026-105959?

CVE-2026-105959 is a high-severity vulnerability in Red Hat Enterprise Linux 6, published on 16 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A flaw was found in spice-server. The GLZ encoder dictionary restore path truncates a size_t allocation size to int when calling the malloc callback, allowing a malicious authenticated SPICE client during VM live migration to trigger a massive heap buffer overflow by sending a crafted max_encoders value in migration data.

Weakness: CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2026-105959?


## How do I fix CVE-2026-105959?

Apply the vendor's patch.

## Is CVE-2026-105959 being exploited?

There is no known exploitation of CVE-2026-105959 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-105959 and fix it if it is affected.

What it is: CVE-2026-105959 is a high-severity vulnerability in Red Hat Enterprise Linux 6, published on 16 Oct 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-2026-105959 in the wild and no public exploit code.

Affected product: Red Hat Enterprise Linux 6. 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-2026-105959/ (Markdown: https://insights.sbomify.com/CVE-2026-105959/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-105959
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-105959
- OSV: https://osv.dev/vulnerability/CVE-2026-105959

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-105959/
Summaries are generated and may contain mistakes; the official description above is the record.