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Linux Kernel EUVD-2026-27776

| CVE-2026-43216 MEDIUM
NULL Pointer Dereference (CWE-476)
2026-05-06 Linux GHSA-r977-p9g8-m7hx
5.5
CVSS 3.1
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CVSS VectorNVD

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

4
Analysis Generated
May 11, 2026 - 19:37 vuln.today
CVSS changed
May 11, 2026 - 19:37 NVD
5.5 (MEDIUM)
Patch available
May 06, 2026 - 13:32 EUVD
CVE Published
May 06, 2026 - 11:28 nvd
MEDIUM 5.5

DescriptionNVD

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.

AnalysisAI

Denial of service in the Linux kernel's net subsystem via deadlock in skb_may_tx_timestamp() when socket timestamp completion occurs in interrupt context while sk_callback_lock is write-locked, affecting local attackers with user privileges on systems with network drivers that complete TX timestamps from dedicated interrupt handlers.

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EUVD-2026-27776 vulnerability details – vuln.today

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