{"cve":"CVE-2021-47245","nvd":{"published":"2024-05-21T15:15:13.550","modified":"2026-08-04T10:16:54.730","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: synproxy: Fix out of bounds when parsing TCP options\n\nThe TCP option parser in synproxy (synproxy_parse_options) could read\none byte out of bounds. When the length is 1, the execution flow gets\ninto the loop, reads one byte of the opcode, and if the opcode is\nneither TCPOPT_EOL nor TCPOPT_NOP, it reads one more byte, which exceeds\nthe 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 an early return when length < 0 to avoid calling\nskb_header_pointer with negative length.","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/576c1526b4d83c44ad7b673cb841f36cbc6cb6c4","https://git.kernel.org/stable/c/5fc177ab759418c9537433e63301096e733fb915","https://git.kernel.org/stable/c/674b5f0c6a4fc5d3abce877048290cea6091fcb1","https://git.kernel.org/stable/c/6defc77d48eff74075b80ad5925061b2fc010d98","https://git.kernel.org/stable/c/7d9a9a1a88a3da574e019b4de756bc73337b3b0b"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:50:30.954589733+00:00"},"epss":{"cve":"CVE-2021-47245","score":0.00784,"percentile":0.56061,"date":"2026-11-01"},"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."]}