{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-21911 in the wild and no public exploit code.","fix":"No fix has been published for CVE-2026-21911 yet. Limit exposure of the affected software until one is available.","what":"CVE-2026-21911 is a high-severity denial of service vulnerability in Juniper Junos Os Evolved, 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-2026-21911 and fix it if it is affected.\n\nWhat it is: CVE-2026-21911 is a high-severity denial of service vulnerability in Juniper Junos Os Evolved, 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-2026-21911 in the wild and no public exploit code.\n\nAffected product: Juniper Junos Os Evolved. 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-2026-21911/ (Markdown: https://insights.sbomify.com/CVE-2026-21911/index.md)","id":"CVE-2026-21911","markdown":"https://insights.sbomify.com/CVE-2026-21911/index.md","name":"CVE-2026-21911","record":{"aliases":["GHSA-6fvr-r66p-5w4v"],"analysis":{"component_type":"network_device","fix_type":"upgrade","impacts":["denial_of_service"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Junos OS Evolved","requires_auth":"none","summary":"An unauthenticated attacker can cause high CPU usage and stop MAC learning by flapping the management interface on Junos OS Evolved devices.","user_interaction":"not_required","vuln_class":"denial_of_service"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"juniper","cpe":[{"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:Amber","version":"4.0"},"cwes":[{"id":"CWE-682","name":"Incorrect Calculation"}],"description":"An Incorrect Calculation vulnerability in the Layer 2 Control\n\nProtocol \n\n Daemon (l2cpd) of Juniper Networks Junos OS Evolved allows an unauthenticated network-adjacent attacker flapping the management interface to cause the learning of new MACs over label-switched interfaces (LSI) to stop while generating a flood of logs, resulting in high CPU usage.\n\nWhen the issue is seen, the following log message will be generated:\n\nop:1 flag:0x6 mac:xx:xx:xx:xx:xx:xx bd:2 ifl:13302 reason:0(REASON_NONE) i-op:6(INTRNL_OP_HW_FORCE_DELETE) status:10 lstatus:10 err:26(GETIFBD_VALIDATE_FAILED) err-reason 4(IFBD_VALIDATE_FAIL_EPOCH_MISMATCH) hw_wr:0x4 ctxsync:0 fwdsync:0  rtt-id:51 p_ifl:0  fwd_nh:0 svlbnh:0 event:- smask:0x100000000 dmask:0x0 mplsmask 0x1 act:0x5800 extf:0x0 pfe-id 0 hw-notif-ifl 13302 programmed-ifl 4294967295 pseudo-vtep underlay-ifl-idx 0 stack:GET_MAC, ALLOCATE_MAC, GET_IFL, GET_IFF, GET_IFBD, STOP, \n\nThis issue affects Junos OS Evolved: \n\n  *  all versions before 21.4R3-S7-EVO, \n  *  from 22.2 before 22.2R3-S4-EVO, \n  *  from 22.3 before 22.3R3-S3-EVO, \n  *  from 22.4 before 22.4R3-S2-EVO, \n  *  from 23.2 before 23.2R2-S1-EVO, \n  *  from 23.4 before 23.4R1-S2-EVO, 23.4R2-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 Evolved: Flapping management interface causes MAC learning on label-switched interfaces to stop","id":"CVE-2026-21911","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"juniper:junos_os_evolved","products":["juniper:junos_os_evolved"],"type":"denial_of_service","year":"2026"},"n_packages":0,"n_references":2,"next":{"headline":"Junos OS: MX10k Series: 'show system firmware' CLI command may lead to LC480 or LC2101 line card reset","id":"CVE-2026-21912"},"packages":[],"prev":{"headline":"Junos OS: EX4k Series, QFX5k Series: In an EVPN-VXLAN configuration link flaps cause Inter-VNI traffic drop","id":"CVE-2026-21910"},"products":["Junos OS Evolved"],"published":"2026-01-15","related":[{"cvss_score":9.3,"headline":"Junos OS Evolved: PTX Series: A vulnerability allows a unauthenticated, network-based attacker to execute code as root","id":"CVE-2026-21902","kev_date_added":null,"published":"2026-02-25"},{"cvss_score":8.8,"headline":"Junos OS Evolved: Shell Injection vulnerability in the gNOI server","id":"CVE-2023-28983","kev_date_added":null,"published":"2023-04-17"},{"cvss_score":8.7,"headline":"Denial of service in Junos OS Evolved","id":"CVE-2025-21599","kev_date_added":null,"published":"2025-01-09"},{"cvss_score":8.7,"headline":"Junos OS Evolved: TCP session state is not always cleared on the Routing Engine leading to DoS","id":"CVE-2024-47502","kev_date_added":null,"published":"2024-10-11"},{"cvss_score":8.7,"headline":"Junos OS Evolved: ACX 7000 Series: Protocol specific DDoS configuration affects other protocols","id":"CVE-2024-39531","kev_date_added":null,"published":"2024-07-11"},{"cvss_score":8.7,"headline":"Junos OS Evolved: A high rate of SSH connections causes a Denial of Service","id":"CVE-2024-39562","kev_date_added":null,"published":"2024-07-10"},{"cvss_score":8.5,"headline":"Junos OS Evolved: Local, authenticated attacker can gain privileged access to FPCs","id":"CVE-2026-33788","kev_date_added":null,"published":"2026-04-09"}],"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 attacker can cause high CPU usage and stop MAC learning by flapping the management interface on Junos OS Evolved devices.","url":"https://insights.sbomify.com/CVE-2026-21911/"}