{"cve":"CVE-2021-41991","nvd":{"published":"2021-10-18T14:15:10.333","modified":"2026-06-17T04:09:07.460","status":"Modified","description":"The in-memory certificate cache in strongSwan before 5.9.4 has a remote integer overflow upon receiving many requests with different certificates to fill the cache and later trigger the replacement of cache entries. The code attempts to select a less-often-used cache entry by means of a random number generator, but this is not done correctly. Remote code execution might be a slight possibility.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-190"],"references":["https://cert-portal.siemens.com/productcert/pdf/ssa-539476.pdf","https://github.com/strongswan/strongswan/releases/tag/5.9.4","https://lists.debian.org/debian-lts-announce/2021/10/msg00014.html","https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5FJSATD2R2XHTG4P63GCMQ2N7EWKMME5/","https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WQSQ3BEC22NF4NCDZVCT4P3Q2ZIAJXGJ/"],"products":["debian:debian_linux","fedoraproject:fedora","siemens:cp_1543-1_firmware","siemens:scalance_sc622-2c_firmware","siemens:scalance_sc632-2c_firmware","siemens:scalance_sc636-2c_firmware","siemens:scalance_sc642-2c_firmware","siemens:scalance_sc646-2c_firmware","siemens:simatic_cp_1242-7_gprs_v2_firmware","siemens:simatic_cp_1243-1_firmware","siemens:simatic_cp_1243-7_lte\\/us_firmware","siemens:simatic_cp_1542sp-1_firmware","siemens:simatic_cp_1542sp-1_irc_firmware","siemens:simatic_cp_1543sp-1_firmware","siemens:simatic_net_cp1243-7_lte_eu_firmware","siemens:simatic_net_cp_1243-8_irc_firmware","siemens:simatic_net_cp_1545-1_firmware","siemens:sinema_remote_connect_server","siemens:siplus_et_200sp_cp_1542sp-1_irc_tx_rail_firmware","siemens:siplus_et_200sp_cp_1543sp-1_isec_firmware","siemens:siplus_et_200sp_cp_1543sp-1_isec_tx_rail_firmware","siemens:siplus_net_cp_1543-1_firmware","siemens:siplus_s7-1200_cp_1243-1_firmware","siemens:siplus_s7-1200_cp_1243-1_rail_firmware","strongswan:strongswan"],"source":"nvd","synced_at":"2026-10-19T21:24:39.218183596+00:00"},"epss":{"cve":"CVE-2021-41991","score":0.05301,"percentile":0.92586,"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."]}