{"answers":{"affected":"It affects 2 products.","exploited":"There is no known exploitation of CVE-2026-21909 in the wild and no public exploit code.","fix":"No fix has been published for CVE-2026-21909 yet. Limit exposure of the affected software until one is available.","what":"CVE-2026-21909 is a high-severity denial of service vulnerability in Juniper Junos, published on 15 Jan 2026. It can only be exploited from the same machine or local network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-21909 and fix it if it is affected.\n\nWhat it is: CVE-2026-21909 is a high-severity denial of service vulnerability in Juniper Junos, published on 15 Jan 2026. It can only be exploited from the same machine or local network, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-21909 in the wild and no public exploit code.\n\nAffected product: Juniper Junos. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-21909/ (Markdown: https://insights.sbomify.com/CVE-2026-21909/index.md)","id":"CVE-2026-21909","markdown":"https://insights.sbomify.com/CVE-2026-21909/index.md","name":"CVE-2026-21909","record":{"aliases":["GHSA-cf3w-5gm7-wvp9"],"analysis":{"component_type":"network_device","fix_type":"upgrade","impacts":["denial_of_service"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Juniper Junos OS","requires_auth":"none","summary":"An unauthenticated adjacent attacker can crash the routing daemon via IS-IS packets, causing a denial of service on Juniper devices.","user_interaction":"not_required","vuln_class":"denial_of_service"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"juniper","cpe":[{"product":"junos","vendor":"juniper"},{"product":"junos_os_evolved","vendor":"juniper"}],"cvss":{"score":7.1,"severity":"high","source":"cna","vector":"CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/V:C/RE:M/U:Green","version":"4.0"},"cwes":[{"id":"CWE-401","name":"Missing Release of Memory after Effective Lifetime"}],"description":"A Missing Release of Memory after Effective Lifetime vulnerability in the routing protocol daemon (rpd) Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated attacker controlling an adjacent IS-IS neighbor to send a specific update packet causing a memory leak. Continued receipt and processing of these packets will exhaust all available memory, crashing rpd and creating a Denial of Service (DoS) condition.\n\nMemory usage can be monitored through the use of the 'show task memory detail' command. For example:\n\nuser@junos\u003e show task memory detail | match ted-infra\n  TED-INFRA-COOKIE             25     1072       28     1184       229\n\nuser@junos\u003e \n\nshow task memory detail | match ted-infra\n  TED-INFRA-COOKIE             31     1360       34     1472       307\n\nThis issue affects:\n\nJunos OS: \n\n  *  from 23.2 before 23.2R2, \n  *  from 23.4 before 23.4R1-S2, 23.4R2, \n  *  from 24.1 before 24.1R2; \n\nJunos OS Evolved: \n\n  *  from 23.2 before 23.2R2-EVO, \n  *  from 23.4 before 23.4R1-S2-EVO, 23.4R2-EVO, \n  *  from 24.1 before 24.1R2-EVO.\n\nThis issue does not affect Junos OS versions before 23.2R1 or Junos OS Evolved versions before 23.2R1-EVO.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":null,"headline":"Junos OS and Junos OS Evolved: Receipt of specific IS-IS update packet causes memory leak leading to RPD crash","id":"CVE-2026-21909","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"juniper:junos","products":["juniper:junos","juniper:junos_os_evolved"],"type":"denial_of_service","year":"2026"},"n_packages":0,"n_references":2,"next":{"headline":"Junos OS: EX4k Series, QFX5k Series: In an EVPN-VXLAN configuration link flaps cause Inter-VNI traffic drop","id":"CVE-2026-21910"},"packages":[],"prev":{"headline":"Use after free in Junos OS","id":"CVE-2026-21908"},"products":["Junos OS","Junos OS Evolved"],"published":"2026-01-15","related":[{"cvss_score":9.8,"headline":"Juniper Junos OS EX Series and SRX Series PHP External Variable Modification","id":"CVE-2023-36845","kev_date_added":"2023-11-13","published":"2023-08-17"},{"cvss_score":8.8,"headline":"Juniper Junos OS Path Traversal","id":"CVE-2020-1631","kev_date_added":"2022-03-25","published":"2020-05-04"},{"cvss_score":6.7,"headline":"Juniper Junos OS Improper Isolation or Compartmentalization","id":"CVE-2025-21590","kev_date_added":"2025-03-13","published":"2025-03-12"},{"cvss_score":5.3,"headline":"Juniper Junos OS SRX Series Missing Authentication for Critical Function","id":"CVE-2023-36851","kev_date_added":"2023-11-13","published":"2023-09-26"},{"cvss_score":5.3,"headline":"Juniper Junos OS EX Series PHP External Variable Modification","id":"CVE-2023-36844","kev_date_added":"2023-11-13","published":"2023-08-17"},{"cvss_score":5.3,"headline":"Juniper Junos OS SRX Series Missing Authentication for Critical Function","id":"CVE-2023-36846","kev_date_added":"2023-11-13","published":"2023-08-17"},{"cvss_score":5.3,"headline":"Juniper Junos OS EX Series Missing Authentication for Critical Function","id":"CVE-2023-36847","kev_date_added":"2023-11-13","published":"2023-08-17"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-01-15","vendors":["Juniper Networks"]},"summary":"An unauthenticated adjacent attacker can crash the routing daemon via IS-IS packets, causing a denial of service on Juniper devices.","url":"https://insights.sbomify.com/CVE-2026-21909/"}