# CVE-2026-74747: ipvs: revalidate ihl to prevent out-of-bounds access

> A local attacker can trigger an out-of-bounds access in the Linux kernel IPVS module by manipulating IP header fields, potentially causing a crash or information leak.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/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:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 26 Aug 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-97830, BELL-CVE-2026-74747, DEBIAN-CVE-2026-74747, GHSA-769p-7f5g-9f2g, UBUNTU-CVE-2026-74747

## What is CVE-2026-74747?

CVE-2026-74747 is a high-severity memory corruption vulnerability in Linux, published on 26 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:

ipvs: revalidate ihl to prevent out-of-bounds access

While the outer IP header is already pulled into the skb head,
we must be careful and revalidate the embedded headers after
reading them from the skb frags to prevent out-of-bounds
access.

One such place reported by Sashiko is ip_vs_nat_icmp() where
local process can change the ihl field and after
skb_ensure_writable() we can see larger value which is a
problem for the ip_send_check(cih) calls.

Add check to drop the packet if the ihl field is changed.

## Which versions are affected by CVE-2026-74747?


## How do I fix CVE-2026-74747?

Apply the vendor's patch.

## Is CVE-2026-74747 being exploited?

There is no known exploitation of CVE-2026-74747 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74747 and fix it if it is affected.

What it is: CVE-2026-74747 is a high-severity memory corruption vulnerability in Linux, published on 26 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-74747 in the wild and no public exploit code.

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-2026-74747/ (Markdown: https://insights.sbomify.com/CVE-2026-74747/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74747
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74747
- OSV: https://osv.dev/vulnerability/CVE-2026-74747

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74747/
Summaries are generated and may contain mistakes; the official description above is the record.