{"id":"CVE-2021-47293","state":"PUBLISHED","title":"net/sched: act_skbmod: Skip non-Ethernet packets","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: act_skbmod: Skip non-Ethernet packets\n\nCurrently tcf_skbmod_act() assumes that packets use Ethernet as their L2\nprotocol, which is not always the case.  As an example, for CAN devices:\n\n\t$ ip link add dev vcan0 type vcan\n\t$ ip link set up vcan0\n\t$ tc qdisc add dev vcan0 root handle 1: htb\n\t$ tc filter add dev vcan0 parent 1: protocol ip prio 10 \\\n\t\tmatchall action skbmod swap mac\n\nDoing the above silently corrupts all the packets.  Do not perform skbmod\nactions for non-Ethernet packets.","publishedAt":"2024-05-21T14:35:17.373Z","updatedAt":"2026-05-11T13:51:41.284Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"86da71b57383d40993cb90baafb3735cffe5d800","status":"affected","lessThan":"e4fdca366806f6bab374d1a95e626a10a3854b0c","versionType":"git"},{"version":"86da71b57383d40993cb90baafb3735cffe5d800","status":"affected","lessThan":"a88414fb1117f2fe65fb88e45ba694e1d09d5024","versionType":"git"},{"version":"86da71b57383d40993cb90baafb3735cffe5d800","status":"affected","lessThan":"071729150be9e1d1b851b70efb6d91ee9269d57b","versionType":"git"},{"version":"86da71b57383d40993cb90baafb3735cffe5d800","status":"affected","lessThan":"34f1e1f657fae2891b485a3b2b95fe4d2aef9f0d","versionType":"git"},{"version":"86da71b57383d40993cb90baafb3735cffe5d800","status":"affected","lessThan":"727d6a8b7ef3d25080fad228b2c4a1d4da5999c6","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/act_skbmod.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.9","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.9","versionType":"semver"},{"version":"4.19.199","status":"unaffected","lessThanOrEqual":"4.19.*","versionType":"semver"},{"version":"5.4.136","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.54","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.13.6","status":"unaffected","lessThanOrEqual":"5.13.*","versionType":"semver"},{"version":"5.14","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/act_skbmod.c"]}],"references":["https://git.kernel.org/stable/c/e4fdca366806f6bab374d1a95e626a10a3854b0c","https://git.kernel.org/stable/c/a88414fb1117f2fe65fb88e45ba694e1d09d5024","https://git.kernel.org/stable/c/071729150be9e1d1b851b70efb6d91ee9269d57b","https://git.kernel.org/stable/c/34f1e1f657fae2891b485a3b2b95fe4d2aef9f0d","https://git.kernel.org/stable/c/727d6a8b7ef3d25080fad228b2c4a1d4da5999c6"],"weaknesses":[],"ingestedAt":"2026-10-29T19:49:19.404Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2021/47xxx/CVE-2021-47293.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2021-47293","state":"PUBLISHED","datePublished":"2024-05-21T14:35:17.373Z","dateUpdated":"2026-05-11T13:51:41.284Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2024-05-21T13:27:52.130Z"},"containers":{"cna":{"title":"net/sched: act_skbmod: Skip non-Ethernet packets","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: act_skbmod: Skip non-Ethernet packets\n\nCurrently tcf_skbmod_act() assumes that packets use Ethernet as their L2\nprotocol, which is not always the case.  As an example, for CAN devices:\n\n\t$ ip link add dev vcan0 type vcan\n\t$ ip link set up vcan0\n\t$ tc qdisc add dev vcan0 root handle 1: htb\n\t$ tc filter add dev vcan0 parent 1: protocol ip prio 10 \\\n\t\tmatchall action skbmod swap mac\n\nDoing the above silently corrupts all the packets.  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