# CVE-2026-62436: grant-table: version change racing with other operations

> A race condition in Xen's grant table version switching allows attackers to cause denial of service or privilege escalation.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 Jul 2026
- **Updated:** 28 Jul 2026
- **Also known as:** ALPINE-CVE-2026-62436, DEBIAN-CVE-2026-62436, GHSA-6j24-4j62-qj29, UBUNTU-CVE-2026-62436

## What is CVE-2026-62436?

CVE-2026-62436 is a medium-severity vulnerability in Xen, published on 28 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

[This CNA information record relates to multiple CVEs; the
text explains which aspects/vulnerabilities correspond to which CVE.]

With the introduction of Grant Table v2 came the requirement to be able to
switch between versions.  Switching from v1 to v2 reduces the number of
valid grant references, as a bigger shared entry structure is then needed
while the shared table doesn't change size.  Switching from v2 back to v1
the status frames, which are separate in v2, go away.

Code holding, but intermediately dropping and then re-acquiring the grant
table lock, sometimes wrongly assumes that said properties wouldn't change
across the window in time where the lock is not being held.

The v1 -> v2 issue is CVE-2026-62435.

The v2 -> v1 issue is CVE-2026-62436.

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2026-62436?


## How do I fix CVE-2026-62436?

Apply the vendor's patch.

## Is CVE-2026-62436 being exploited?

There is no known exploitation of CVE-2026-62436 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-62436 and fix it if it is affected.

What it is: CVE-2026-62436 is a medium-severity vulnerability in Xen, published on 28 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-62436 in the wild and no public exploit code.

Affected product: Xen. 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-2026-62436/ (Markdown: https://insights.sbomify.com/CVE-2026-62436/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-62436
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-62436
- OSV: https://osv.dev/vulnerability/CVE-2026-62436

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-62436/
Summaries are generated and may contain mistakes; the official description above is the record.