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TI-2021-21951 Aliases CVE-2021-47293GHSA-qqw5-j897-27cf

net/sched: act_skbmod: Skip non-Ethernet packets

Priority LOW 34Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · High · High
Fix status
Partial Red Hat: 3 fixed, 1 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.

Summary

In the Linux kernel, the following vulnerability has been resolved: net/sched: act_skbmod: Skip non-Ethernet packets Currently tcf_skbmod_act() assumes that packets use Ethernet as their L2 protocol, which is not always the case. As an example, for CAN devices: $ ip link add dev vcan0 type vcan $ ip link set up vcan0 $ tc qdisc add dev vcan0 root handle 1: htb $ tc filter add dev vcan0 parent 1: protocol ip prio 10 \ matchall action skbmod swap mac Doing the above silently corrupts all the packets. Do not perform skbmod actions for non-Ethernet packets.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00234 14th percentileScored 2026-11-08
Fix Partial Linux (Linux): 4.19.199, 5.4.136, 5.10.54 +2Red Hat: 1 advisoryRed Hat: 3 fixed, 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
LinuxLinux4.9 and later4.19.199, 5.4.136, 5.10.54, 5.13.6, 5.14Patch availableCNA
  • Linux VendorLinux Affected 4.9 and later Fixed in 4.19.199, 5.4.136, 5.10.54, 5.13.6, 5.14 Patch available CNA

CPE configurations NVD · 3

CPEVersionsRoleVendor
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*4.9 to before 4.19.199; 4.20 to before 5.4.136; 5.5 to before 5.10.54; 5.11 to before 5.13.6VulnerableLinux
cpe:2.3:o:linux:linux_kernel:5.14:rc1:*:*:*:*:*:*5.14 rc1VulnerableLinux
cpe:2.3:o:linux:linux_kernel:5.14:rc2:*:*:*:*:*:*5.14 rc2VulnerableLinux
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 4.9 to before 4.19.199; 4.20 to before 5.4.136; 5.5 to before 5.10.54; 5.11 to before 5.13.6 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:5.14:rc1:*:*:*:*:*:* Versions 5.14 rc1 Vulnerable ·Linux
  • cpe:2.3:o:linux:linux_kernel:5.14:rc2:*:*:*:*:*:* Versions 5.14 rc2 Vulnerable ·Linux

Remediation

  • Fix · CNA Linux (Linux) Fixed in 4.19.199, 5.4.136, 5.10.54, 5.13.6, 5.14

Red Hat 1 advisory

  • RHSA-2024:4447 Released 2024-07-10 · Red Hat rating Important
    kernel security update
    • Red Hat Enterprise Linux BaseOS AUS (v.8.6) bpftool-4.18.0-372.111.1.el8_6, kernel-4.18.0-372.111.1.el8_6, kernel-abi-stablelists-4.18.0-372.111.1.el8_6 +14
    • Red Hat Enterprise Linux BaseOS E4S (v.8.6) bpftool-4.18.0-372.111.1.el8_6, kernel-4.18.0-372.111.1.el8_6, kernel-abi-stablelists-4.18.0-372.111.1.el8_6 +19
    • Red Hat Enterprise Linux BaseOS TUS (v.8.6) bpftool-4.18.0-372.111.1.el8_6, kernel-4.18.0-372.111.1.el8_6, kernel-abi-stablelists-4.18.0-372.111.1.el8_6 +14

Vendor assessments

Red Hat

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

ProductStatusPlan or fix
Red Hat Enterprise Linux 7AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux BaseOS AUS (v.8.6)Fixed RHSA-2024:4447
Red Hat Enterprise Linux BaseOS E4S (v.8.6)Fixed RHSA-2024:4447
Red Hat Enterprise Linux BaseOS TUS (v.8.6)Fixed RHSA-2024:4447
Not affected: 3 products
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-47293
  2. 2026-10-03 Alias added: GHSA-qqw5-j897-27cf
  3. 2026-11-05 Affected versions changed · Red Hat

References

Patch 5

  • 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-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
  • TI-2021-05514 Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE KEVCVSS 3.1HIGH 8.3
See all 15278 →

Sources

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