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TI-2026-75901 Aliases CVE-2026-98773GHSA-fp39-rj9v-7xc4

Use-after-free in Linux kernel cdc-acm driver after USB disconnect

Priority LOW 22Published · Updated

Key facts

Attack vector
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Privileges required
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User interaction
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Attack complexity
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Impact type
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Confidentiality · integrity · availability
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Fix status
Partial Red Hat: 1 without a fix

No CVSS vector from any source. Fix status from CNA and Red Hat.

Summary

The cdc-acm USB modem driver in the Linux kernel can restart USB request blocks when a port shuts down after the device was disconnected. This race lets the driver access DMA buffers that a concurrent disconnect has already freed, which causes a use-after-free. Affected versions span several Linux kernel stable branches.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

Description from the CNA

In the Linux kernel, the following vulnerability has been resolved: USB: cdc-acm: skip URB restart in port_shutdown if disconnected acm_port_shutdown() is called from the tty-port machinery whenever the last user closes the port. acm_disconnect() sets acm->disconnected and calls tty_port_tty_vhangup(), which eventually triggers port_shutdown(). At that point acm_disconnect() has already called acm_poison_urbs() and is about to free the control and read URBs. However, acm_port_shutdown() unconditionally calls acm_unpoison_urbs() and, when the ALWAYS_POLL_CTRL quirk is set, immediately re-submits the ctrlurb and all read URBs. If the concurrent acm_disconnect() then frees those URBs and their DMA buffers while they are in-flight, the result is a use-after-free in acm_ctrl_irq() or acm_read_bulk_callback() accessing the freed DMA memory. Fix by checking acm->disconnected after draining the delayed anchor and returning early: if we are in a disconnect path the URBs must remain poisoned and must not be resubmitted. The early return is placed after the delayed-anchor drain loop because that loop only cancels write-side accounting (wb->use = false and autopm counter) and does not touch the hardware path.

Why it matters now

EPSS 0.00172 6th percentileScored 2026-11-07
Fix Partial Linux (Linux): 6.1.191, 6.6.160, 6.12.113 +5Red Hat: 1 without a fix

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
LinuxLinux6.1.175 to before 6.1.191; 6.6.136 to before 6.6.160; 6.12.83 to before 6.12.113; 6.18.24 to before 6.18.56; 6.19.14 to before 6.20; 7.0.1 to before 7.16.1.191, 6.6.160, 6.12.113, 6.18.56, 6.20, 7.1Patch availableCNA
LinuxLinux7.1 and later6.1.191, 6.6.160, 6.12.113, 6.18.56, 7.2.10, 7.3Patch availableCNA
  • Linux VendorLinux Affected 6.1.175 to before 6.1.191; 6.6.136 to before 6.6.160; 6.12.83 to before 6.12.113; 6.18.24 to before 6.18.56; 6.19.14 to before 6.20; 7.0.1 to before 7.1 Fixed in 6.1.191, 6.6.160, 6.12.113, 6.18.56, 6.20, 7.1 Patch available CNA
  • Linux VendorLinux Affected 7.1 and later Fixed in 6.1.191, 6.6.160, 6.12.113, 6.18.56, 7.2.10, 7.3 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*——Linux
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions — — ·Linux

Remediation

Upgrade the Linux kernel to 6.1.191, 6.6.160, 6.12.113, 6.18.56, 6.20, 7.1, 7.2.10 or 7.3, depending on the branch in use. Red Hat lists Red Hat Enterprise Linux 6 as affected with no fix planned.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

  • Fix · CNA Linux (Linux) Fixed in 6.1.191, 6.6.160, 6.12.113, 6.18.56, 6.20, 7.1
  • Fix · CNA Linux (Linux) Fixed in 6.1.191, 6.6.160, 6.12.113, 6.18.56, 7.2.10, 7.3

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
Not affected: 6 products
  • Red Hat Enterprise Linux 10
  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9
  • Red Hat OpenShift Container Platform 4
  • Red Hat OpenShift Container Platform 5

Timeline

  1. 2026-10-18 Threatist record created from CVE-2026-98773
  2. 2026-10-18 Alias added: GHSA-fp39-rj9v-7xc4
  3. 2026-10-19 Fix available: Linux/[email protected] · CNA
  4. 2026-10-21 Fix available: Linux/[email protected], Linux/Linux@d86775e79838d7d2e38ccf506a7d0f8e2dd4d5d0 · CNA
  5. 2026-10-21 1 new reference · CNA
  6. 2026-10-23 Affected versions changed · Red Hat
  7. 2026-10-23 CVSS score added · Red Hat
  8. 2026-10-30 Fix available: Linux/[email protected], Linux/Linux@d97da42e9de577dc827d4e8866e6971deefe2d9c · CNA
  9. 2026-10-30 1 new reference · CNA
  10. 2026-11-06 Affected versions changed · Red Hat

References

Other 6

  • TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
  • TI-2021-02452 Incorrect authorization in Ubuntu linux kernel KEVCVSS 3.1HIGH 8.8
  • TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
  • TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
  • TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
See all 21741 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences