{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2025-21681 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2025-21681 is a medium-severity denial of service vulnerability in Linux kernel, published on 31 Jan 2025. 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-2025-21681 and fix it if it is affected.\n\nWhat it is: CVE-2025-21681 is a medium-severity denial of service vulnerability in Linux kernel, published on 31 Jan 2025. 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-2025-21681 in the wild and no public exploit code.\n\nAffected product: Linux kernel. 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-2025-21681/ (Markdown: https://insights.sbomify.com/CVE-2025-21681/index.md)","id":"CVE-2025-21681","markdown":"https://insights.sbomify.com/CVE-2025-21681/index.md","name":"CVE-2025-21681","record":{"aliases":["AZL-57055","BELL-CVE-2025-21681","DEBIAN-CVE-2025-21681","GHSA-2x4f-r6q9-v77h","UBUNTU-CVE-2025-21681"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel","requires_auth":"low_privilege","summary":"An attacker can cause a system lockup and require a reboot by sending traffic to an unregistering network device in the Linux kernel's Open vSwitch module.","user_interaction":"not_required","vuln_class":"denial_of_service"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[{"product":"linux_kernel","vendor":"linux"}],"cvss":{"score":5.5,"severity":"medium","source":"nvd","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"cwes":[{"id":"CWE-835","name":"Loop with Unreachable Exit Condition"}],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nopenvswitch: fix lockup on tx to unregistering netdev with carrier\n\nCommit in a fixes tag attempted to fix the issue in the following\nsequence of calls:\n\n    do_output\n    -\u003e ovs_vport_send\n       -\u003e dev_queue_xmit\n          -\u003e __dev_queue_xmit\n             -\u003e netdev_core_pick_tx\n                -\u003e skb_tx_hash\n\nWhen device is unregistering, the 'dev-\u003ereal_num_tx_queues' goes to\nzero and the 'while (unlikely(hash \u003e= qcount))' loop inside the\n'skb_tx_hash' becomes infinite, locking up the core forever.\n\nBut unfortunately, checking just the carrier status is not enough to\nfix the issue, because some devices may still be in unregistering\nstate while reporting carrier status OK.\n\nOne example of such device is a net/dummy.  It sets carrier ON\non start, but it doesn't implement .ndo_stop to set the carrier off.\nAnd it makes sense, because dummy doesn't really have a carrier.\nTherefore, while this device is unregistering, it's still easy to hit\nthe infinite loop in the skb_tx_hash() from the OVS datapath.  There\nmight be other drivers that do the same, but dummy by itself is\nimportant for the OVS ecosystem, because it is frequently used as a\npacket sink for tcpdump while debugging OVS deployments.  And when the\nissue is hit, the only way to recover is to reboot.\n\nFix that by also checking if the device is running.  The running\nstate is handled by the net core during unregistering, so it covers\nunregistering case better, and we don't really need to send packets\nto devices that are not running anyway.\n\nWhile only checking the running state might be enough, the carrier\ncheck is preserved.  The running and the carrier states seem disjoined\nthroughout the code and different drivers.  And other core functions\nlike __dev_direct_xmit() check both before attempting to transmit\na packet.  So, it seems safer to check both flags in OVS as well.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"openvswitch: fix lockup on tx to unregistering netdev with carrier","id":"CVE-2025-21681","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"linux:linux_kernel","products":["linux:linux_kernel"],"type":"denial_of_service","year":"2025"},"n_packages":0,"n_references":7,"next":{"headline":"eth: bnxt: always recalculate features after XDP clearing, fix null-deref","id":"CVE-2025-21682"},"packages":[],"prev":{"headline":"pktgen: Avoid out-of-bounds access in get_imix_entries","id":"CVE-2025-21680"},"products":["Linux"],"published":"2025-01-31","related":[{"cvss_score":8.8,"headline":"Linux Kernel Out-of-Bounds Write","id":"CVE-2026-53266","kev_date_added":"2026-09-18","published":"2026-06-25"},{"cvss_score":8.8,"headline":"Linux Kernel Improper Input Validation","id":"CVE-2013-6282","kev_date_added":"2022-09-15","published":"2013-11-19"},{"cvss_score":8.4,"headline":"Linux Kernel Heap-Based Buffer Overflow","id":"CVE-2022-0185","kev_date_added":"2024-08-21","published":"2022-02-11"},{"cvss_score":8.4,"headline":"Linux Kernel Privilege Escalation","id":"CVE-2013-2094","kev_date_added":"2022-09-15","published":"2013-05-14"},{"cvss_score":7.8,"headline":"Linux Kernel Unspecified","id":"CVE-2026-53362","kev_date_added":"2026-08-27","published":"2026-07-04"},{"cvss_score":7.8,"headline":"Linux Kernel Missing Initialization of a Variable","id":"CVE-2026-46300","kev_date_added":"2026-10-28","published":"2026-05-23"},{"cvss_score":7.8,"headline":"Linux Kernel Race Condition","id":"CVE-2025-39964","kev_date_added":"2026-09-18","published":"2025-10-13"}],"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":null,"exploitation":null,"technical_impact":null},"state":"PUBLISHED","updated":"2026-05-23","vendors":["Linux"]},"summary":"An attacker can cause a system lockup and require a reboot by sending traffic to an unregistering network device in the Linux kernel's Open vSwitch module.","url":"https://insights.sbomify.com/CVE-2025-21681/"}