# CVE-2026-80901: ipvs: fix the checksum validations

> Missing checksum validation in Linux kernel IPVS allows bypassing integrity checks for ICMPv6 packets, potentially enabling traffic manipulation.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Sep 2026
- **Updated:** 4 Sep 2026
- **Also known as:** AZL-99662, BELL-CVE-2026-80901, DEBIAN-CVE-2026-80901, GHSA-mp45-vjm2-gvhg, UBUNTU-CVE-2026-80901

## What is CVE-2026-80901?

CVE-2026-80901 is a vulnerability in Linux, published on 4 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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

ipvs: fix the checksum validations

ip_vs_in_icmp_v6() is missing checksum validation for ICMPv6
packets from clients. In fact, as for TCP/UDP we should
validate the checksum for ICMP packets only when we
mangle the packets on MASQ or on reply for tunnel.

Also, Sashiko points out that handle_response_icmp() being
common for IPv4 and IPv6 is missing the pseudo-header
calculation while validating ICMPv6 messages from real
servers which is a problem if checksum is not validated
by the hardware.

Fix the problems by creating ip_vs_checksum_common_check()
helper and use it for TCP/UDP/ICMP both for IPv4 and IPv6.
Rely on the nf_checksum() for validating the ICMP messages
but use it also for TCP and UDP.

Use correct IP offset for IP_VS_DBG_RL_PKT for TCP/UDP/SCTP.

IPVS packets (TCP/UDP/SCTP/ICMP) do not need checksum
validation on LOCAL_OUT (local clients or local real
servers) and on FORWARD (traffic from servers on LAN).
Do it only on LOCAL_IN, in case nf_checksum() is not
called on PRE_ROUTING.

Also, ip_vs_checksum_complete() can be marked static.

## Which versions are affected by CVE-2026-80901?


## How do I fix CVE-2026-80901?

Apply the vendor's patch.

## Is CVE-2026-80901 being exploited?

There is no known exploitation of CVE-2026-80901 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80901 and fix it if it is affected.

What it is: CVE-2026-80901 is a vulnerability in Linux, published on 4 Sep 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-2026-80901 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-2026-80901/ (Markdown: https://insights.sbomify.com/CVE-2026-80901/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80901
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80901
- OSV: https://osv.dev/vulnerability/CVE-2026-80901

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80901/
Summaries are generated and may contain mistakes; the official description above is the record.