{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2025-21891 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2025-21891 is a medium-severity memory corruption vulnerability in Linux kernel, published on 27 Mar 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-2025-21891 and fix it if it is affected.\n\nWhat it is: CVE-2025-21891 is a medium-severity memory corruption vulnerability in Linux kernel, published on 27 Mar 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-2025-21891 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-2025-21891/ (Markdown: https://insights.sbomify.com/CVE-2025-21891/index.md)","id":"CVE-2025-21891","markdown":"https://insights.sbomify.com/CVE-2025-21891/index.md","name":"CVE-2025-21891","record":{"aliases":["AZL-60331","BELL-CVE-2025-21891","DEBIAN-CVE-2025-21891","GHSA-fcmx-wvw9-587f","ROOT-OS-DEBIAN-11-CVE-2025-21891","ROOT-OS-UBUNTU-2204-CVE-2025-21891","ROOT-OS-UBUNTU-2404-CVE-2025-21891","UBUNTU-CVE-2025-21891"],"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":"A missing check in the Linux kernel ipvlan driver allows uninitialized memory access, potentially causing a system crash.","user_interaction":"not_required","vuln_class":"memory_corruption"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[{"product":"linux_kernel","vendor":"linux"}],"cvss":{"score":5.5,"severity":"medium","source":"cisa-adp","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-908","name":"Use of Uninitialized Resource"}],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipvlan: ensure network headers are in skb linear part\n\nsyzbot found that ipvlan_process_v6_outbound() was assuming\nthe IPv6 network header isis present in skb-\u003ehead [1]\n\nAdd the needed pskb_network_may_pull() calls for both\nIPv4 and IPv6 handlers.\n\n[1]\nBUG: KMSAN: uninit-value in __ipv6_addr_type+0xa2/0x490 net/ipv6/addrconf_core.c:47\n  __ipv6_addr_type+0xa2/0x490 net/ipv6/addrconf_core.c:47\n  ipv6_addr_type include/net/ipv6.h:555 [inline]\n  ip6_route_output_flags_noref net/ipv6/route.c:2616 [inline]\n  ip6_route_output_flags+0x51/0x720 net/ipv6/route.c:2651\n  ip6_route_output include/net/ip6_route.h:93 [inline]\n  ipvlan_route_v6_outbound+0x24e/0x520 drivers/net/ipvlan/ipvlan_core.c:476\n  ipvlan_process_v6_outbound drivers/net/ipvlan/ipvlan_core.c:491 [inline]\n  ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:541 [inline]\n  ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:605 [inline]\n  ipvlan_queue_xmit+0xd72/0x1780 drivers/net/ipvlan/ipvlan_core.c:671\n  ipvlan_start_xmit+0x5b/0x210 drivers/net/ipvlan/ipvlan_main.c:223\n  __netdev_start_xmit include/linux/netdevice.h:5150 [inline]\n  netdev_start_xmit include/linux/netdevice.h:5159 [inline]\n  xmit_one net/core/dev.c:3735 [inline]\n  dev_hard_start_xmit+0x247/0xa20 net/core/dev.c:3751\n  sch_direct_xmit+0x399/0xd40 net/sched/sch_generic.c:343\n  qdisc_restart net/sched/sch_generic.c:408 [inline]\n  __qdisc_run+0x14da/0x35d0 net/sched/sch_generic.c:416\n  qdisc_run+0x141/0x4d0 include/net/pkt_sched.h:127\n  net_tx_action+0x78b/0x940 net/core/dev.c:5484\n  handle_softirqs+0x1a0/0x7c0 kernel/softirq.c:561\n  __do_softirq+0x14/0x1a kernel/softirq.c:595\n  do_softirq+0x9a/0x100 kernel/softirq.c:462\n  __local_bh_enable_ip+0x9f/0xb0 kernel/softirq.c:389\n  local_bh_enable include/linux/bottom_half.h:33 [inline]\n  rcu_read_unlock_bh include/linux/rcupdate.h:919 [inline]\n  __dev_queue_xmit+0x2758/0x57d0 net/core/dev.c:4611\n  dev_queue_xmit include/linux/netdevice.h:3311 [inline]\n  packet_xmit+0x9c/0x6c0 net/packet/af_packet.c:276\n  packet_snd net/packet/af_packet.c:3132 [inline]\n  packet_sendmsg+0x93e0/0xa7e0 net/packet/af_packet.c:3164\n  sock_sendmsg_nosec net/socket.c:718 [inline]","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":"ipvlan: ensure network headers are in skb linear part","id":"CVE-2025-21891","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"linux:linux_kernel","products":["linux:linux_kernel"],"type":"memory_corruption","year":"2025"},"n_packages":0,"n_references":5,"next":{"headline":"RDMA/mlx5: Fix the recovery flow of the UMR QP","id":"CVE-2025-21892"},"packages":[],"prev":{"headline":"idpf: fix checksums set in idpf_rx_rsc()","id":"CVE-2025-21890"},"products":["Linux"],"published":"2025-03-27","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":"no","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-05-11","vendors":["Linux"]},"summary":"A missing check in the Linux kernel ipvlan driver allows uninitialized memory access, potentially causing a system crash.","url":"https://insights.sbomify.com/CVE-2025-21891/"}