# CVE-2026-98485: netfilter: ip6t_rt: fix zero-address non-strict match out-of-bounds read

> A crafted IPv6 packet can trigger an out-of-bounds read in the Linux kernel netfilter module, causing a kernel panic or information disclosure.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/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:** 18 Oct 2026
- **Updated:** 24 Oct 2026
- **Also known as:** AZL-108650, BELL-CVE-2026-98485, DEBIAN-CVE-2026-98485, GHSA-mhfj-849g-frgh, UBUNTU-CVE-2026-98485

## What is CVE-2026-98485?

CVE-2026-98485 is a high-severity memory corruption vulnerability in Linux, published on 18 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

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

netfilter: ip6t_rt: fix zero-address non-strict match out-of-bounds read

rt_mt6_check() permits rules to be configured with rtinfo->addrnr == 0
even when address matching (IP6T_RT_FST_MASK) is requested.

In the IP6T_RT_FST_NSTRICT path, rt_mt6() evaluates packet routing
addresses against rtinfo->addrs[i] and terminates backwards at the bottom
of the loop:

    if (ipv6_addr_equal(ap, &rtinfo->addrs[i])) {
        i++;
    }
    if (i == rtinfo->addrnr)
        break;

When addrnr is 0, if the first packet address matches rtinfo->addrs[0],
i is incremented to 1. Because i is now strictly greater than addrnr (0),
the loop termination condition (i == rtinfo->addrnr) is bypassed and will
never be satisfied.

If a crafted IPv6 packet contains matching routing addresses, i will
advance past IP6T_RT_HOPS (16). The subsequent call to ipv6_addr_equal()
reads beyond struct ip6t_rt, triggering UBSAN/KASAN out-of-bounds warnings
or kernel panics.

Fix this by:
1. Rejecting rules in rt_mt6_check() where IP6T_RT_FST_MASK is set but
   rtinfo->addrnr is zero.
2. In rt_mt6(), moving the termination condition (i < rtinfo->addrnr)
   into the for-loop header condition and removing the backwards break
   at the end of the loop body.

## Which versions are affected by CVE-2026-98485?


## How do I fix CVE-2026-98485?

Apply the vendor's patch.

## Is CVE-2026-98485 being exploited?

There is no known exploitation of CVE-2026-98485 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98485 and fix it if it is affected.

What it is: CVE-2026-98485 is a high-severity memory corruption vulnerability in Linux, published on 18 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-2026-98485 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-2026-98485/ (Markdown: https://insights.sbomify.com/CVE-2026-98485/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98485
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98485
- OSV: https://osv.dev/vulnerability/CVE-2026-98485

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98485/
Summaries are generated and may contain mistakes; the official description above is the record.