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

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Summary

CVECVE-2026-31474
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-22 14:16:44 UTC
Updated2026-07-15 02:19:48 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from ADP

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.000180000 probability, percentile 0.048130000 (date 2026-04-27)

Problem Types: CWE-416 | CWE-364 | CWE-364 Signal Handler Race Condition

VersionSourceTypeScoreSeverityVector
3.1ADPCVSS7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.10b0ca135-0b70-47e7-9f44-1890c2a1c46cSecondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 96d1c81e6a0478535342dff6c730adb076cd84e8 cb3d6efa78460e6d50bf68806d0db66265709f64 git Not specified
CNA Linux Linux affected 96d1c81e6a0478535342dff6c730adb076cd84e8 9649d051e54413049c009638ec1dc23962c884a4 git Not specified
CNA Linux Linux affected 96d1c81e6a0478535342dff6c730adb076cd84e8 eec8a1b18a79600bd4419079dc0026c1db72a830 git Not specified
CNA Linux Linux affected 96d1c81e6a0478535342dff6c730adb076cd84e8 2e62e7051eca75a7f2e3d52d62ec10d7d7aa358c git Not specified
CNA Linux Linux affected 96d1c81e6a0478535342dff6c730adb076cd84e8 424e95d62110cdbc8fd12b40918f37e408e35a92 git Not specified
CNA Linux Linux affected 6.4 Not specified
CNA Linux Linux unaffected 6.4 semver Not specified
CNA Linux Linux unaffected 6.6.131 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.80 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.21 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.11 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0 * original_commit_for_fix Not specified
ADP Red Hat Red Hat Enterprise Linux 10 unaffected 0:6.12.0-211.26.1.el10_2 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support unaffected 0:6.12.0-55.82.1.el10_0 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 9 unaffected 0:5.14.0-687.17.1.el9_8 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 6 Not specified Not specified
ADP Red Hat Red Hat Enterprise Linux 7 Not specified Not specified
ADP Red Hat Red Hat Enterprise Linux 7 Not specified Not specified
ADP Red Hat Red Hat Enterprise Linux 8 Not specified Not specified
ADP Red Hat Red Hat Enterprise Linux 8 Not specified Not specified
ADP Red Hat Red Hat Enterprise Linux 9 Not specified Not specified

References

ReferenceSourceLinkTags
bugzilla.redhat.com/show_bug.cgi 0b0ca135-0b70-47e7-9f44-1890c2a1c46c bugzilla.redhat.com
access.redhat.com/security/cve/CVE-2026-31474 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:27789 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
git.kernel.org/stable/c/9649d051e54413049c009638ec1dc23962c884a4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/424e95d62110cdbc8fd12b40918f37e408e35a92 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/eec8a1b18a79600bd4419079dc0026c1db72a830 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/cb3d6efa78460e6d50bf68806d0db66265709f64 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
access.redhat.com/errata/RHSA-2026:27731 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-31474.json 0b0ca135-0b70-47e7-9f44-1890c2a1c46c security.access.redhat.com
git.kernel.org/stable/c/2e62e7051eca75a7f2e3d52d62ec10d7d7aa358c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
access.redhat.com/errata/RHSA-2026:27288 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

SourceTimeEvent
ADP2026-04-22T00:00:00.000ZReported to Red Hat.
ADP2026-04-22T00:00:00.000ZMade public.

Solutions

ADP: RHSA-2026:27731: Red Hat Enterprise Linux AppStream EUS (v. 10.0), Red Hat Enterprise Linux BaseOS EUS (v. 10.0), Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0), Red Hat Enterprise Linux Real Time EUS (v. 10.0), Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0)

ADP: RHSA-2026:27288: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10), Red Hat Enterprise Linux Real Time (v. 10), Red Hat Enterprise Linux Real Time for NFV (v. 10)

ADP: RHSA-2026:27789: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux BaseOS (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9), Red Hat Enterprise Linux Real Time (v. 9), Red Hat Enterprise Linux Real Time for NFV (v. 9)

Workarounds

ADP: Systems which do not require it can blocklist the `can_isotp` module to prevent it from being loaded. See https://access.redhat.com/solutions/41278 for more information.

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