# CVE-2026-98600: Bluetooth: RFCOMM: Reject short EA=0 frames in rfcomm_recv_frame()

> A flaw in the Linux kernel Bluetooth RFCOMM implementation allows attackers to cause a denial of service by sending malformed short frames.

- **Severity:** Not scored
- **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:** 18 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-98600, DEBIAN-CVE-2026-98600, GHSA-hpgr-cqmv-php2, UBUNTU-CVE-2026-98600

## What is CVE-2026-98600?

CVE-2026-98600 is a denial of service vulnerability in Linux, published on 18 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:

Bluetooth: RFCOMM: Reject short EA=0 frames in rfcomm_recv_frame()

While rfcomm_recv_frame() verifies that skb->len is at least
sizeof(*hdr) + 1 (4 bytes: 3-byte header + 1-byte FCS), an RFCOMM frame
with an extended 2-byte length field (!__test_ea(hdr->len)) has a 4-byte
header plus a 1-byte FCS (5 bytes minimum, sizeof(*hdr) + 2).

When a 4-byte RFCOMM frame with EA == 0 arrives:
1. The initial skb->len < sizeof(*hdr) + 1 check passes (4 < 4 is false).
2. Trimming the FCS byte decrements skb->len to 3.
3. If __check_fcs() succeeds, skb_pull(skb, 4) fails (4 > 3) and returns
   NULL without advancing skb->data.
4. Because the return value of skb_pull() is ignored, the un-pulled
   3-byte struct rfcomm_hdr remains at skb->data and is either queued as
   application payload via rfcomm_recv_data() or parsed as a multiplexer
   control command via rfcomm_recv_mcc() on DLCI 0.

Fix this by extending the length check in rfcomm_recv_frame() to also
require skb->len >= sizeof(*hdr) + 2 when !__test_ea(hdr->len).

## Which versions are affected by CVE-2026-98600?


## How do I fix CVE-2026-98600?

Apply the vendor's patch.

## Is CVE-2026-98600 being exploited?

There is no known exploitation of CVE-2026-98600 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98600 and fix it if it is affected.

What it is: CVE-2026-98600 is a denial of service vulnerability in Linux, published on 18 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-2026-98600 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-2026-98600/ (Markdown: https://insights.sbomify.com/CVE-2026-98600/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98600
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98600
- OSV: https://osv.dev/vulnerability/CVE-2026-98600

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98600/
Summaries are generated and may contain mistakes; the official description above is the record.