{"cve":"CVE-2021-47243","nvd":{"published":"2024-05-21T15:15:13.403","modified":"2026-08-04T10:16:54.377","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsch_cake: Fix out of bounds when parsing TCP options and header\n\nThe TCP option parser in cake qdisc (cake_get_tcpopt and\ncake_tcph_may_drop) could read one byte out of bounds. When the length\nis 1, the execution flow gets into the loop, reads one byte of the\nopcode, and if the opcode is neither TCPOPT_EOL nor TCPOPT_NOP, it reads\none more byte, which exceeds the length of 1.\n\nThis fix is inspired by commit 9609dad263f8 (\"ipv4: tcp_input: fix stack\nout of bounds when parsing TCP options.\").\n\nv2 changes:\n\nAdded doff validation in cake_get_tcphdr to avoid parsing garbage as TCP\nheader. Although it wasn't strictly an out-of-bounds access (memory was\nallocated), garbage values could be read where CAKE expected the TCP\nheader if doff was smaller than 5.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","score":7.1},"cwes":["CWE-125"],"references":["https://git.kernel.org/stable/c/3371392c60e2685af30bd4547badd880f5df2b3f","https://git.kernel.org/stable/c/3b491dd593d582ceeb27aa617600712a6bd14246","https://git.kernel.org/stable/c/4cefa061fc63f4d2dff5ab4083f43857cd7a2335","https://git.kernel.org/stable/c/595897ef118d6fe66690c4fc5b572028c9da95b7","https://git.kernel.org/stable/c/ba91c49dedbde758ba0b72f57ac90b06ddf8e548"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:50:30.954589733+00:00"},"epss":{"cve":"CVE-2021-47243","score":0.00261,"percentile":0.17942,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}