{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2025-21857 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2025-21857 is a medium-severity vulnerability in Linux kernel, published on 12 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-2025-21857 and fix it if it is affected.\n\nWhat it is: CVE-2025-21857 is a medium-severity vulnerability in Linux kernel, published on 12 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-2025-21857 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-2025-21857/ (Markdown: https://insights.sbomify.com/CVE-2025-21857/index.md)","id":"CVE-2025-21857","markdown":"https://insights.sbomify.com/CVE-2025-21857/index.md","name":"CVE-2025-21857","record":{"aliases":["AZL-58511","BELL-CVE-2025-21857","DEBIAN-CVE-2025-21857","GHSA-6rpq-7wmg-7qjv","ROOT-OS-UBUNTU-2404-CVE-2025-21857","UBUNTU-CVE-2025-21857"],"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 NULL pointer dereference in the Linux kernel's traffic control subsystem allows local attackers to cause a system crash.","user_interaction":"not_required","vuln_class":"null_dereference"},"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-476","name":"NULL Pointer Dereference"}],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_api: fix error handling causing NULL dereference\n\ntcf_exts_miss_cookie_base_alloc() calls xa_alloc_cyclic() which can\nreturn 1 if the allocation succeeded after wrapping. This was treated as\nan error, with value 1 returned to caller tcf_exts_init_ex() which sets\nexts-\u003eactions to NULL and returns 1 to caller fl_change().\n\nfl_change() treats err == 1 as success, calling tcf_exts_validate_ex()\nwhich calls tcf_action_init() with exts-\u003eactions as argument, where it\nis dereferenced.\n\nExample trace:\n\nBUG: kernel NULL pointer dereference, address: 0000000000000000\nCPU: 114 PID: 16151 Comm: handler114 Kdump: loaded Not tainted 5.14.0-503.16.1.el9_5.x86_64 #1\nRIP: 0010:tcf_action_init+0x1f8/0x2c0\nCall Trace:\n tcf_action_init+0x1f8/0x2c0\n tcf_exts_validate_ex+0x175/0x190\n fl_change+0x537/0x1120 [cls_flower]","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":"net/sched: cls_api: fix error handling causing NULL dereference","id":"CVE-2025-21857","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"linux:linux_kernel","products":["linux:linux_kernel"],"type":"null_dereference","year":"2025"},"n_packages":0,"n_references":4,"next":{"headline":"geneve: Fix use-after-free in geneve_find_dev().","id":"CVE-2025-21858"},"packages":[],"prev":{"headline":"s390/ism: add release function for struct device","id":"CVE-2025-21856"},"products":["Linux"],"published":"2025-03-12","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 NULL pointer dereference in the Linux kernel's traffic control subsystem allows local attackers to cause a system crash.","url":"https://insights.sbomify.com/CVE-2025-21857/"}