{"id":"CVE-2021-47013","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet:emac/emac-mac: Fix a use after free in emac_mac_tx_buf_send\n\nIn emac_mac_tx_buf_send, it calls emac_tx_fill_tpd(..,skb,..).\nIf some error happens in emac_tx_fill_tp…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet:emac/emac-mac: Fix a use after free in emac_mac_tx_buf_send\n\nIn emac_mac_tx_buf_send, it calls emac_tx_fill_tpd(..,skb,..).\nIf some error happens in emac_tx_fill_tp…","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-416"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 4.9, < 4.9.269","linux_kernel >= 4.10, < 4.14.233","linux_kernel >= 4.15, < 4.19.191","linux_kernel >= 4.20, < 5.4.119","linux_kernel >= 5.5, < 5.10.37","linux_kernel >= 5.11, < 5.11.21","linux_kernel >= 5.12, < 5.12.4"],"patched":["linux_kernel 5.12.4"],"published":"2024-02-28","updated":"2026-08-04","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2021-47013","references":[{"url":"https://git.kernel.org/stable/c/16d8c44be52e3650917736d45f5904384a9da834","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/55fcdd1258faaecca74b91b88cc0921f9edd775d","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6d72e7c767acbbdd44ebc7d89c6690b405b32b57","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/8c06f34785068b87e2b560534c77c163d6c6dca7","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/9dc373f74097edd0e35f3393d6248eda8d1ba99d","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c7f75d11fe72913d2619f97b2334b083cd7bb955","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/dc1b438a35773d030be0ee80d9c635c3e558a322","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e407495ba6788a67d1bd41714158c079e340879b","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/16d8c44be52e3650917736d45f5904384a9da834","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/55fcdd1258faaecca74b91b88cc0921f9edd775d","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/6d72e7c767acbbdd44ebc7d89c6690b405b32b57","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/8c06f34785068b87e2b560534c77c163d6c6dca7","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/9dc373f74097edd0e35f3393d6248eda8d1ba99d","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/c7f75d11fe72913d2619f97b2334b083cd7bb955","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/dc1b438a35773d030be0ee80d9c635c3e558a322","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/e407495ba6788a67d1bd41714158c079e340879b","label":"af854a3a-2127-422b-91ae-364da2661108"}],"tags":["nvd"],"epss":0.00783,"epssPercentile":0.54533,"ingestedAt":"2026-08-04T10:39:39.148Z","slug":"CVE-2021-47013","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnet:emac/emac-mac: Fix a use after free in emac_mac_tx_buf_send\n\nIn emac_mac_tx_buf_send, it calls emac_tx_fill_tpd(..,skb,..).\nIf some error happens in emac_tx_fill_tpd(), the skb will be freed via\ndev_kfree_skb(skb) in error branch of emac_tx_fill_tpd().\nBut the freed skb is still used via skb->len by netdev_sent_queue(,skb->len).\n\nAs i observed that emac_tx_fill_tpd() haven't modified the value of skb->len,\nthus my patch assigns skb->len to 'len' before the possible free and\nuse 'len' instead of skb->len later.\n\n## Affected\n\n- `linux_kernel >= 4.9, < 4.9.269`\n- `linux_kernel >= 4.10, < 4.14.233`\n- `linux_kernel >= 4.15, < 4.19.191`\n- `linux_kernel >= 4.20, < 5.4.119`\n- `linux_kernel >= 5.5, < 5.10.37`\n- `linux_kernel >= 5.11, < 5.11.21`\n- `linux_kernel >= 5.12, < 5.12.4`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 5.12.4`","depth":"midnight","depthScore":54,"depthScoreParts":{"impact":53.9,"likelihood":0.2,"exploitation":0,"ransomware":0},"changes":[]}