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High severity7.8NVD Advisory· Published Feb 27, 2025· Updated May 12, 2026

CVE-2025-21762

CVE-2025-21762

Description

In the Linux kernel, the following vulnerability has been resolved:

arp: use RCU protection in arp_xmit()

arp_xmit() can be called without RTNL or RCU protection.

Use RCU protection to avoid potential UAF.

AI Insight

LLM-synthesized narrative grounded in this CVE's description and references.

A use-after-free vulnerability in the Linux kernel's ARP subsystem (arp_xmit) can occur when the function is called without proper RTNL or RCU locking, potentially allowing local privilege escalation.

CVE-2025-21762 is a vulnerability in the Linux kernel's Address Resolution Protocol (ARP) implementation, specifically within the arp_xmit() function. The root cause is that arp_xmit() can be invoked without holding the RTNL lock or under RCU protection, leading to a potential use-after-free (UAF) condition when the underlying network device or ARP cache entry is concurrently freed.

Attack

Surface and Exploitation To exploit this vulnerability, an attacker needs local access to the system and the ability to trigger arp_xmit() calls without proper locking. This could be achieved through crafted network operations or by manipulating ARP-related system calls. The missing synchronization allows a race condition: while one thread is transmitting an ARP packet, another thread may free the associated memory structures, leading to a UAF.

Impact

A successful exploit could allow an attacker to crash the system (denial of service) or, in the worst case, execute arbitrary code with kernel privileges, leading to full compromise of the affected system.

Mitigation

The vulnerability has been patched in the Linux kernel. Users should apply the relevant kernel updates as soon as they are available from their distribution vendors. Siemens has also acknowledged the issue and lists it as affecting the SIMATIC S7-1500 TM MFP's GNU/Linux subsystem [1], with no fix currently released for that specific product.

References
  1. SSA-265688

AI Insight generated on May 20, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.

Affected products

92

Patches

0

No patches discovered yet.

Vulnerability mechanics

AI mechanics synthesis has not run for this CVE yet.

References

12

News mentions

0

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