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VulnerabilityPublished Updated

CVE-2025-21681: Linux kernel · Infinite Loop

Source GCVE Database

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Not known to be exploited · CVSS 5.5 Medium.

Data as of 30 Oct 2026, 01:08 UTC

CVSS 3.1 base score
5.5Medium
How severe the flaw is on the 0–10 CVSS scale.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 31 Jan 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

AI-suggested

A fix for this vulnerability has been implemented in the Linux kernel by modifying openvswitch to check both the running and carrier states of network devices before transmitting packets. Users should apply the official kernel updates containing this fix once available. Until patched, avoiding use of affected devices in unregistering states or using net/dummy devices as packet sinks may reduce exposure, but the primary mitigation is to update the kernel. No vendor advisory or patch links were provided, so check the Linux kernel mailing lists or distribution security advisories for the official fixed versions.

Description

CVE-2025-21681 is a medium severity vulnerability in the Linux kernel's openvswitch component. It involves a lockup condition triggered during packet transmission to a network device that is unregistering but still reports carrier status as active. The flaw causes an infinite loop in the skb_tx_hash function, leading to a kernel hang requiring a reboot to recover. The issue arises because some devices, such as net/dummy, do not clear carrier status properly during unregistering. The fix involves checking both the running and carrier states of the device before transmitting packets.

References

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