{"cve":"CVE-2024-21585","nvd":{"published":"2024-01-12T01:15:46.053","modified":"2026-06-17T07:09:45.833","status":"Modified","description":"An Improper Handling of Exceptional Conditions vulnerability in BGP session processing of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated network-based attacker, using specific timing outside the attacker's control, to flap BGP sessions and cause the routing protocol daemon (rpd) process to crash and restart, leading to a Denial of Service (DoS) condition. Continued BGP session flapping will create a sustained Denial of Service (DoS) condition.\n\nThis issue only affects routers configured with non-stop routing (NSR) enabled. Graceful Restart (GR) helper mode, enabled by default, is also required for this issue to be exploitable.\n\n\nNote: NSR is not supported on the SRX Series and is therefore not affected by this vulnerability.\nWhen the BGP session flaps on the NSR-enabled router, the device enters GR-helper/LLGR-helper mode due to the peer having negotiated GR/LLGR-restarter capability and the backup BGP requests for replication of the GR/LLGR-helper session, master BGP schedules, and initiates replication of GR/LLGR stale routes to the backup BGP. In this state, if the BGP session with the BGP peer comes up again, unsolicited replication is initiated for the peer without cleaning up the ongoing GR/LLGR-helper mode replication. This parallel two instances of replication for the same peer leads to the assert if the BGP session flaps again.\n\nThis issue affects:\n\nJuniper Networks Junos OS\n\n\n\n  *  All versions earlier than 20.4R3-S9;\n  *  21.2 versions earlier than 21.2R3-S7;\n  *  21.3 versions earlier than 21.3R3-S5;\n  *  21.4 versions earlier than 21.4R3-S5;\n  *  22.1 versions earlier than 22.1R3-S4;\n  *  22.2 versions earlier than 22.2R3-S3;\n  *  22.3 versions earlier than 22.3R3-S1;\n  *  22.4 versions earlier than 22.4R2-S2, 22.4R3;\n  *  23.2 versions earlier than 23.2R1-S1, 23.2R2.\n\n\n\n\nJuniper Networks Junos OS Evolved\n\n\n\n  *  All versions earlier than 21.3R3-S5-EVO;\n  *  21.4 versions earlier than 21.4R3-S5-EVO;\n  *  22.1 versions earlier than 22.1R3-S4-EVO;\n  *  22.2 versions earlier than 22.2R3-S3-EVO;\n  *  22.3 versions earlier than 22.3R3-S1-EVO;\n  *  22.4 versions earlier than 22.4R2-S2-EVO, 22.4R3-EVO;\n  *  23.2 versions earlier than 23.2R1-S1-EVO, 23.2R2-EVO.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","score":5.9},"cwes":["CWE-755"],"references":["https://supportportal.juniper.net/JSA75723","https://supportportal.juniper.net/s/article/MX-GR-and-LLGR-capability-and-compatibility-changes-after-15-1-release","https://www.first.org/cvss/calculator/4.0#CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L","https://supportportal.juniper.net/JSA75723","https://supportportal.juniper.net/s/article/MX-GR-and-LLGR-capability-and-compatibility-changes-after-15-1-release"],"products":["juniper:junos","juniper:junos_os_evolved"],"source":"nvd","synced_at":"2026-10-19T21:43:38.875533635+00:00"},"epss":{"cve":"CVE-2024-21585","score":0.00625,"percentile":0.49973,"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."]}