Bug 2461478 (CVE-2026-31623)

Summary: CVE-2026-31623 kernel: net: usb: cdc-phonet: fix skb frags[] overflow in rx_complete()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's cdc-phonet driver. A malicious USB device, pretending to be a CDC Phonet modem, can exploit this vulnerability by sending an unlimited number of large data transfers. This can cause an overflow in the kernel's internal data buffer (skb_shared_info->frags[] array), leading to a Denial of Service (DoS) condition where the system may become unresponsive or crash.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-04-24 15:03:51 UTC
In the Linux kernel, the following vulnerability has been resolved:

net: usb: cdc-phonet: fix skb frags[] overflow in rx_complete()

A malicious USB device claiming to be a CDC Phonet modem can overflow
the skb_shared_info->frags[] array by sending an unbounded sequence of
full-page bulk transfers.

Drop the skb and increment the length error when the frag limit is
reached.  This matches the same fix that commit f0813bcd2d9d ("net:
wwan: t7xx: fix potential skb->frags overflow in RX path") did for the
t7xx driver.