{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2025-21632 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2025-21632 is a medium-severity vulnerability in Linux kernel, published on 19 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-2025-21632 and fix it if it is affected.\n\nWhat it is: CVE-2025-21632 is a medium-severity vulnerability in Linux kernel, published on 19 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-2025-21632 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-2025-21632/ (Markdown: https://insights.sbomify.com/CVE-2025-21632/index.md)","id":"CVE-2025-21632","markdown":"https://insights.sbomify.com/CVE-2025-21632/index.md","name":"CVE-2025-21632","record":{"aliases":["BELL-CVE-2025-21632","DEBIAN-CVE-2025-21632","GHSA-gjg2-r77w-jx7q","UBUNTU-CVE-2025-21632"],"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 local attacker can trigger a kernel warning and potential crash by using ptrace to access shadow stack registers when the feature is disabled.","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":"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-476","name":"NULL Pointer Dereference"}],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nx86/fpu: Ensure shadow stack is active before \"getting\" registers\n\nThe x86 shadow stack support has its own set of registers. Those registers\nare XSAVE-managed, but they are \"supervisor state components\" which means\nthat userspace can not touch them with XSAVE/XRSTOR.  It also means that\nthey are not accessible from the existing ptrace ABI for XSAVE state.\nThus, there is a new ptrace get/set interface for it.\n\nThe regset code that ptrace uses provides an -\u003eactive() handler in\naddition to the get/set ones. For shadow stack this -\u003eactive() handler\nverifies that shadow stack is enabled via the ARCH_SHSTK_SHSTK bit in the\nthread struct. The -\u003eactive() handler is checked from some call sites of\nthe regset get/set handlers, but not the ptrace ones. This was not\nunderstood when shadow stack support was put in place.\n\nAs a result, both the set/get handlers can be called with\nXFEATURE_CET_USER in its init state, which would cause get_xsave_addr() to\nreturn NULL and trigger a WARN_ON(). The ssp_set() handler luckily has an\nssp_active() check to avoid surprising the kernel with shadow stack\nbehavior when the kernel is not ready for it (ARCH_SHSTK_SHSTK==0). That\ncheck just happened to avoid the warning.\n\nBut the -\u003eget() side wasn't so lucky. It can be called with shadow stacks\ndisabled, triggering the warning in practice, as reported by Christina\nSchimpe:\n\nWARNING: CPU: 5 PID: 1773 at arch/x86/kernel/fpu/regset.c:198 ssp_get+0x89/0xa0\n[...]\nCall Trace:\n\u003cTASK\u003e\n? show_regs+0x6e/0x80\n? ssp_get+0x89/0xa0\n? __warn+0x91/0x150\n? ssp_get+0x89/0xa0\n? report_bug+0x19d/0x1b0\n? handle_bug+0x46/0x80\n? exc_invalid_op+0x1d/0x80\n? asm_exc_invalid_op+0x1f/0x30\n? __pfx_ssp_get+0x10/0x10\n? ssp_get+0x89/0xa0\n? ssp_get+0x52/0xa0\n__regset_get+0xad/0xf0\ncopy_regset_to_user+0x52/0xc0\nptrace_regset+0x119/0x140\nptrace_request+0x13c/0x850\n? wait_task_inactive+0x142/0x1d0\n? do_syscall_64+0x6d/0x90\narch_ptrace+0x102/0x300\n[...]\n\nEnsure that shadow stacks are active in a thread before looking them up\nin the XSAVE buffer. Since ARCH_SHSTK_SHSTK and user_ssp[SHSTK_EN] are\nset at the same time, the active check ensures that there will be\nsomething to find in the XSAVE buffer.\n\n[ dhansen: changelog/subject tweaks ]","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":"x86/fpu: Ensure shadow stack is active before \"getting\" registers","id":"CVE-2025-21632","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":3,"next":{"headline":"This CVE ID has been rejected or withdrawn by its CVE Numbering Authority.","id":"CVE-2025-21633"},"packages":[],"prev":{"headline":"block, bfq: fix waker_bfqq UAF after bfq_split_bfqq()","id":"CVE-2025-21631"},"products":["Linux"],"published":"2025-01-19","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":"2026-05-11","vendors":["Linux"]},"summary":"A local attacker can trigger a kernel warning and potential crash by using ptrace to access shadow stack registers when the feature is disabled.","url":"https://insights.sbomify.com/CVE-2025-21632/"}