# CVE-2026-74580: vhost: reset the vring metadata cache on vring reconfiguration

> A stale cache in the Linux kernel vhost driver allows out-of-bounds memory access, potentially enabling code execution or privilege escalation.

- **Severity:** High 8.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 21 Aug 2026
- **Updated:** 29 Oct 2026
- **Also known as:** AZL-96992, BELL-CVE-2026-74580, DEBIAN-CVE-2026-74580, GHSA-mr6w-hqp3-cg59, UBUNTU-CVE-2026-74580

## What is CVE-2026-74580?

CVE-2026-74580 is a high-severity memory corruption vulnerability in Linux, published on 21 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

vhost: reset the vring metadata cache on vring reconfiguration

vq->meta_iotlb[] caches the vhost_iotlb_map that backs each vring
metadata region, and iotlb_access_ok() returns early on a cache hit,
taking the hit as proof that the region has already been validated:

	if (vhost_vq_meta_fetch(vq, addr, len, type))
		return true;

The cache is reset on VHOST_IOTLB_UPDATE and VHOST_IOTLB_INVALIDATE, on
device IOTLB (re)initialisation and on vq reset, but not when
VHOST_SET_VRING_ADDR replaces vq->desc, vq->avail and vq->used, nor when
VHOST_SET_VRING_NUM changes the region sizes.

With a device IOTLB attached both ioctls are accepted while the vq is
live, and neither validates the addresses at ioctl time: vq_access_ok()
and vq_log_used_access_ok() return true early because the addresses are
GIOVAs, deferring validation to prefetch time.  Once the cache has been
populated that deferred validation no longer runs -- vq_meta_prefetch()
hits the stale entry and returns true -- and vhost_vq_meta_fetch() keeps
translating through the old mapping as

	map->addr + addr - map->start

for an address the mapping no longer covers.  vhost_copy_to_user() and
vhost_copy_from_user() consume the result with __copy_to_user() and
__copy_from_user(), which do not check it either, so a subsequent used
ring update or descriptor fetch accesses memory outside the region the
IOTLB actually maps.

Reset the metadata cache whenever the vring is reconfigured, so the new
addresses are pushed back through iotlb_access_ok()'s slow path.

## Which versions are affected by CVE-2026-74580?


## How do I fix CVE-2026-74580?

Apply the vendor's patch.

## Is CVE-2026-74580 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-74580 exists.

Public exploit code:

- https://github.com/ABC00012345/CVE-2026-74580 (github_poc): https://github.com/ABC00012345/CVE-2026-74580
- Passive internet-wide discovery + responsible-disclosure helper for CVE-2026-74580 (Linux vhost metadata-cache bug) — queries existing scan data (Sonar/Shodan/Censys), triages exposure, and drafts (never auto-sends) notices to owners. (github_poc): https://github.com/V01DL1NG/vghost-watch
- CVE-2026-74580 vhost: reset the vring metadata cache on vring reconfiguration - Exploit (github_poc): https://github.com/YounesHfa/CVE-2026-74580
- A complete guide and workflow for integrating Agile sprints with DevOps CI/CD pipelines. (github_poc): https://github.com/techupdate24/linux-kernel-cve-2026-74580-vghost

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74580 and fix it if it is affected.

What it is: CVE-2026-74580 is a high-severity memory corruption vulnerability in Linux, published on 21 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-74580 exists.

Affected product: Linux. 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-2026-74580/ (Markdown: https://insights.sbomify.com/CVE-2026-74580/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74580
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74580
- OSV: https://osv.dev/vulnerability/CVE-2026-74580

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74580/
Summaries are generated and may contain mistakes; the official description above is the record.