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medium 5.5

CVE-2026-63962 json

usb: typec: tcpm: bound altmode_desc[] per iteration in svdm_consume_modes()

published 3mo ago modified 12d ago also EUVD-2026-45735

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 5%
public exploits
0
none known

Summary

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

usb: typec: tcpm: bound altmode_desc[] per iteration in svdm_consume_modes()

svdm_consume_modes() checks pmdata->altmodes against the array size once before the loop over the count, but forgot to check the bound at every point in the loop.

In the well-behaved SVDM discovery flow this is harmless because each of at most SVID_DISCOVERY_MAX SVIDs contributes at most MODE_DISCOVERY_MAX modes, exactly filling altmode_desc[ALTMODE_DISCOVERY_MAX]. But the CMDT_RSP_ACK handler in tcpm_pd_svdm() does not correlate an incoming ACK with any request the port actually sent. Once port->partner is set, an unsolicited Discover Modes ACK is consumed unconditionally. A broken or malicious port partner can therefore drive altmodes to ALTMODE_DISCOVERY_MAX - 1 via the normal flow, and then send one extra Discover Modes ACK with seven VDOs. Because the pre-loop check passes, the loop could then writes up to five entries past altmode_desc[]. For mode_data_prime the next field in struct tcpm_port is the partner_altmode[] pointer array, which then receives partner-chosen SVID/VDO bytes.

Move the bound check inside the loop so the array can never be indexed past ALTMODE_DISCOVERY_MAX regardless of how many VDOs the partner supplies or how the function was reached.

Patch / fix

  • Linux Linux 6.1.191, 6.6.160, 6.12.93, 6.18.35, 7.0.12, 7.1
  • linux Debian 13 6.12.94-1
  • linux Debian 14 7.0.12-1

debian advisories DEBIAN-CVE-2026-63962

  • linux Ubuntu 26.04 LTS 7.0.0-28.28
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1009.9
  • linux-gcp Ubuntu 26.04 LTS 7.0.0-1008.8
  • linux-gke Ubuntu 26.04 LTS 7.0.0-1003.4
  • linux-ibm Ubuntu 26.04 LTS 7.0.0-1010.10
  • linux-azure Ubuntu 26.04 LTS 7.0.0-1010.10
  • linux-raspi Ubuntu 26.04 LTS 7.0.0-1015.15
  • linux-riscv Ubuntu 26.04 LTS 7.0.0-28.28.1

ubuntu advisories UBUNTU-CVE-2026-63962

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel RHEL 10.2 6.12.0-211.67.1.el10_2
  • rv RHEL 10.2 6.12.0-211.67.1.el10_2
  • perf RHEL 10.2 6.12.0-211.67.1.el10_2
  • rtla RHEL 10.2 6.12.0-211.67.1.el10_2
  • libperf RHEL 10.2 6.12.0-211.67.1.el10_2
  • kernel-rt RHEL 10.2 6.12.0-211.67.1.el10_2
  • kernel-64k RHEL 10.2 6.12.0-211.67.1.el10_2
  • kernel-core RHEL 10.2 6.12.0-211.67.1.el10_2

red hat advisories RHSA-2026:85321

  • kernel-rt Real Time Module 15 SP7 6.4.0-150700.7.72.1
  • kernel-syms-rt Real Time Module 15 SP7 6.4.0-150700.7.72.1
  • kernel-source-rt Real Time Module 15 SP7 6.4.0-150700.7.72.1
  • kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.78.1
  • kernel-syms SLE Module for Development Tools 15 SP7 6.4.0-150700.53.78.1
  • kernel-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.53.78.1
  • kernel-source SLE Module for Development Tools 15 SP7, SLE Module for Basesystem 15 SP7 6.4.0-150700.53.78.1
  • kernel-default SLE Workstation Extension 15 SP7, SLE Module for Legacy 15 SP7, SLE Module for Basesystem 15 SP7 +2 more 6.4.0-150700.53.78.1

suse advisories SUSE-SU-2026:4282-1SUSE-SU-2026:3810-1SUSE-SU-2026:3790-1SUSE-SU-2026:23244-1SUSE-SU-2026:23241-1SUSE-SU-2026:23194-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.37.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.37.1

opensuse advisories openSUSE-SU-2026:21555-1

  • kernel AlmaLinux 9 5.14.0-687.59.1.el9_8
  • rv AlmaLinux 9 5.14.0-687.59.1.el9_8
  • perf AlmaLinux 9 5.14.0-687.59.1.el9_8
  • rtla AlmaLinux 9 5.14.0-687.59.1.el9_8
  • libperf AlmaLinux 9 5.14.0-687.59.1.el9_8
  • kernel-rt AlmaLinux 9 5.14.0-687.59.1.el9_8
  • kernel-64k AlmaLinux 9 5.14.0-687.59.1.el9_8
  • kernel-core AlmaLinux 9 5.14.0-687.59.1.el9_8

almalinux advisories ALSA-2026:86033ALSA-2026:85321

  • kernel Rocky Linux 9 5.14.0-687.59.1.el9_8
  • kernel Rocky Linux 10 6.12.0-211.67.1.el10_2

rocky linux advisories RLSA-2026:86033RLSA-2026:85321

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-63962 updated cvss 7.0

kernel: usb: typec: tcpm: bound altmode_desc[] per iteration in svdm_consume_modes()

  • Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more
    affected: no fix available
  • Red Hat Enterprise Linux kernel-modules-internal 6.12.0-211.67.1.el10_2
    fixed: vendor fix RHSA-2026:85321
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-687.59.1.el9_8, rv 5.14.0-741.20.1.el9_9, perf 5.14.0-687.59.1.el9_8, perf 5.14.0-741.20.1.el9_9, rtla 5.14.0-687.59.1.el9_8, rtla 5.14.0-741.20.1.el9_9, +20 more
    fixed: vendor fix RHSA-2026:86033
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.67.1.el10_2, rv 6.12.0-264.14.1.el10_3, perf 6.12.0-211.67.1.el10_2, perf 6.12.0-264.14.1.el10_3, rtla 6.12.0-211.67.1.el10_2, rtla 6.12.0-264.14.1.el10_3, +20 more
    fixed: vendor fix RHSA-2026:85321
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-687.59.1.el9_8, kernel 5.14.0-741.20.1.el9_9, kernel-64k 5.14.0-687.59.1.el9_8, kernel-64k 5.14.0-741.20.1.el9_9, kernel-core 5.14.0-687.59.1.el9_8, kernel-core 5.14.0-741.20.1.el9_9, +60 more
    fixed: vendor fix RHSA-2026:86033
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.67.1.el10_2, kernel 6.12.0-264.14.1.el10_3, kernel-64k 6.12.0-211.67.1.el10_2, kernel-64k 6.12.0-264.14.1.el10_3, kernel-core 6.12.0-211.67.1.el10_2, kernel-core 6.12.0-264.14.1.el10_3, +62 more
    fixed: vendor fix RHSA-2026:85321
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-687.59.1.el9_8, libperf 5.14.0-741.20.1.el9_9, kernel-debuginfo-common-s390x 5.14.0-687.59.1.el9_8, kernel-debuginfo-common-s390x 5.14.0-741.20.1.el9_9, kernel-debuginfo-common-x86_64 5.14.0-687.59.1.el9_8, kernel-debuginfo-common-x86_64 5.14.0-741.20.1.el9_9, +4 more
    fixed: vendor fix RHSA-2026:86033
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.67.1.el10_2, libperf 6.12.0-264.14.1.el10_3, kernel-debuginfo-common-s390x 6.12.0-211.67.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-264.14.1.el10_3, kernel-debuginfo-common-x86_64 6.12.0-211.67.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-264.14.1.el10_3, +4 more Red Hat Enterprise Linux Hidden (v. 10) kernel-modules-internal 6.12.0-211.67.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.67.1.el10_2
    fixed: vendor fix RHSA-2026:85321
show 5 more
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-687.59.1.el9_8, kernel-rt 5.14.0-741.20.1.el9_9, kernel-rt-64k 5.14.0-687.59.1.el9_8, kernel-rt-64k 5.14.0-741.20.1.el9_9, kernel-rt-core 5.14.0-687.59.1.el9_8, kernel-rt-core 5.14.0-741.20.1.el9_9, +34 more
    fixed: vendor fix RHSA-2026:86033
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.67.1.el10_2, kernel-rt 6.12.0-264.14.1.el10_3, kernel-rt-64k 6.12.0-211.67.1.el10_2, kernel-rt-64k 6.12.0-264.14.1.el10_3, kernel-rt-core 6.12.0-211.67.1.el10_2, kernel-rt-core 6.12.0-264.14.1.el10_3, +34 more
    fixed: vendor fix RHSA-2026:85321
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-687.59.1.el9_8, kernel-rt 5.14.0-741.20.1.el9_9, kernel-rt-core 5.14.0-687.59.1.el9_8, kernel-rt-core 5.14.0-741.20.1.el9_9, kernel-rt-modules 5.14.0-687.59.1.el9_8, kernel-rt-modules 5.14.0-741.20.1.el9_9, +15 more
    fixed: vendor fix RHSA-2026:86033
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.67.1.el10_2, kernel-rt 6.12.0-264.14.1.el10_3, kernel-rt-core 6.12.0-211.67.1.el10_2, kernel-rt-core 6.12.0-264.14.1.el10_3, kernel-rt-modules 6.12.0-211.67.1.el10_2, kernel-rt-modules 6.12.0-264.14.1.el10_3, +15 more
    fixed: vendor fix RHSA-2026:85321
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.16% chance of exploitation in the next 30 days, higher than 5% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.