# CVE-2026-98419: drop_monitor: fix out-of-bounds write in reset_per_cpu_data()

> A local attacker can trigger an out-of-bounds write in the Linux kernel drop_monitor module, potentially leading to memory corruption and privilege escalation.

- **Severity:** High 7.0 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Oct 2026
- **Updated:** 24 Oct 2026
- **Also known as:** AZL-108162, BELL-CVE-2026-98419, DEBIAN-CVE-2026-98419, GHSA-6j59-9ph5-7p77, UBUNTU-CVE-2026-98419

## What is CVE-2026-98419?

CVE-2026-98419 is a high-severity memory corruption vulnerability in Linux, published on 14 Oct 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:

drop_monitor: fix out-of-bounds write in reset_per_cpu_data()

In reset_per_cpu_data(), al is computed as:

    al = sizeof(struct net_dm_alert_msg);
    al += dm_hit_limit * sizeof(struct net_dm_drop_point);
    al += sizeof(struct nlattr);

    skb = genlmsg_new(al, GFP_KERNEL);
    ...
    nla = nla_reserve(skb, NLA_UNSPEC, sizeof(struct net_dm_alert_msg));
    ...
    msg = nla_data(nla);
    memset(msg, 0, al);

Because al includes sizeof(struct nlattr) (the 4-byte attribute header),
genlmsg_new() allocates al bytes of tailroom starting at nla.
However, msg points to nla_data(nla), which is located
sizeof(struct nlattr) bytes past nla. Calling memset(msg, 0, al)
therefore writes al bytes starting from msg, exceeding the allocated
buffer by sizeof(struct nlattr) (4 bytes) and corrupting
skb_shared_info.

Fix this by letting al represent only the payload length, allocating
the skb with genlmsg_new(nla_total_size(al), GFP_KERNEL), and zeroing
al bytes from msg.

## Which versions are affected by CVE-2026-98419?


## How do I fix CVE-2026-98419?

Apply the vendor's patch.

## Is CVE-2026-98419 being exploited?

There is no known exploitation of CVE-2026-98419 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98419 and fix it if it is affected.

What it is: CVE-2026-98419 is a high-severity memory corruption vulnerability in Linux, published on 14 Oct 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-2026-98419 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-2026-98419/ (Markdown: https://insights.sbomify.com/CVE-2026-98419/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98419
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98419
- OSV: https://osv.dev/vulnerability/CVE-2026-98419

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98419/
Summaries are generated and may contain mistakes; the official description above is the record.