What’s Vulnerable › Vulnerabilities

CVE-2021-47520: can: pch_can: pch_can_rx_normal: fix use after free

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2024-05-24 · updated 2026-08-04
• Weakness: CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: can: pch_can: pch_can_rx_normal: fix use after free After calling netif_receive_skb(skb), dereferencing skb is unsafe. Especially, the can_frame cf which aliases skb memory is dereferenced just after the call netif_receive_skb(skb). Reordering the lines solves the issue.

Affected products

• Linux kernel: from 2.6.37 before 4.4.295; from 4.5 before 4.9.293; from 4.10 before 4.14.258; from 4.15 before 4.19.221; from 4.20 before 5.4.165; from 5.5 before 5.10.85 — fixed in 4.14.258, 4.19.221, 4.4.295, 4.9.293, 5.10.85, 5.15.8

How to fix

Upgrade to a fixed version: Linux kernel 4.14.258, 4.19.221, 4.4.295, 4.9.293. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/3a3c46e2eff0577454860a203be1a8295f4acb76
• https://git.kernel.org/stable/c/3e193ef4e0a3f5bf92ede83ef214cb09d01b00aa
• https://git.kernel.org/stable/c/6c73fc931658d8cbc8a1714b326cb31eb71d16a7
• https://git.kernel.org/stable/c/703dde112021c93d6e89443c070e7dbd4dea612e
• https://git.kernel.org/stable/c/94cddf1e9227a171b27292509d59691819c458db
• https://git.kernel.org/stable/c/abb4eff3dcd2e583060082a18a8dbf31f02689d4
• https://git.kernel.org/stable/c/affbad02bf80380a7403885b9fe4a1587d1bb4f3
• https://git.kernel.org/stable/c/bafe343a885c70dddf358379cf0b2a1c07355d8d
• https://git.kernel.org/stable/c/3a3c46e2eff0577454860a203be1a8295f4acb76
• https://git.kernel.org/stable/c/3e193ef4e0a3f5bf92ede83ef214cb09d01b00aa
• https://git.kernel.org/stable/c/6c73fc931658d8cbc8a1714b326cb31eb71d16a7
• https://git.kernel.org/stable/c/703dde112021c93d6e89443c070e7dbd4dea612e

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