HighFix available

can: isotp: fix tx.buf use-after-free in isotp_sendmsg()

Type: advisorySources: OSV

In the Linux kernel, the following vulnerability has been resolved: can: isotp: fix tx.buf use-after-free in isotp_sendmsg() isotp_sendmsg() uses only cmpxchg() on so->tx.state to serialize access to so->tx.buf. isotp_release() waits for ISOTP_IDLE via wait_event_interruptible() and then calls kfree(so->tx.buf). If a signal interrupts the wait_event_interruptible() inside close() while tx.state is ISOTP_SENDING, the loop exits early and release proceeds to force ISOTP_SHUTDOWN and continues to kfree(so->tx.buf) while sendmsg may still be reading so->tx.buf for the final CAN frame in isotp_fill_dataframe(). The so->tx.buf can be allocated once when the standard tx.buf length needs to be extended. Move the kfree() of this potentially extended tx.buf to sk_destruct time when either isotp_sendmsg() and isotp_release() are done.

Products: Kernel
Affected versions: Not specified
Fixed versions: 6.12.80, 6.18.21, 6.19.11, 6.6.131
CVEs: CVE-2026-31474
Confirmed fixed CVEs: Not specified
Updated in this feed: 8 Nov 2026, 03:44 UTC · Revision 1

Source evidence

can: isotp: fix tx.buf use-after-free in isotp_sendmsg()

core-osv · Original source

Published 22 Apr 2026, 13:54 UTC

osv:CVE-2026-31474

Kernel

Fixed versions: 6.6.131, 6.12.80, 6.18.21, 6.19.11

Complete source record

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  "url": "https://osv.dev/vulnerability/CVE-2026-31474",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "can: isotp: fix tx.buf use-after-free in isotp_sendmsg()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: can: isotp: fix tx.buf use-after-free in isotp_sendmsg() isotp_sendmsg() uses only cmpxchg() on so->tx.state to serialize access to so->tx.buf. isotp_release() waits for ISOTP_IDLE via wait_event_interruptible() and then calls kfree(so->tx.buf). If a signal interrupts the wait_event_interruptible() inside close() while tx.state is ISOTP_SENDING, the loop exits early and release proceeds to force ISOTP_SHUTDOWN and continues to kfree(so->tx.buf) while sendmsg may still be reading so->tx.buf for the final CAN frame in isotp_fill_dataframe(). The so->tx.buf can be allocated once when the standard tx.buf length needs to be extended. Move the kfree() of this potentially extended tx.buf to sk_destruct time when either isotp_sendmsg() and isotp_release() are done.",
    "evidence": "osv:CVE-2026-31474",
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      "modified": "2026-10-28T02:30:53.308638550Z",
      "provider": "osv",
      "references": [
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        "https://access.redhat.com/errata/RHSA-2026:27288",
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  "source_id": "core-osv",
  "document_id": 522314,
  "published_at": "2026-04-22T13:54:03.1+00:00"
}