{"answers":{"affected":"It affects 2 products.","exploited":"There is no known exploitation of CVE-2025-39881 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2025-39881 is a high-severity use after free vulnerability in Debian Debian Linux, published on 23 Sep 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-2025-39881 and fix it if it is affected.\n\nWhat it is: CVE-2025-39881 is a high-severity use after free vulnerability in Debian Debian Linux, published on 23 Sep 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-2025-39881 in the wild and no public exploit code.\n\nAffected product: Debian Debian Linux. 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-2025-39881/ (Markdown: https://insights.sbomify.com/CVE-2025-39881/index.md)","id":"CVE-2025-39881","markdown":"https://insights.sbomify.com/CVE-2025-39881/index.md","name":"CVE-2025-39881","record":{"aliases":["AZL-67637","BELL-CVE-2025-39881","DEBIAN-CVE-2025-39881","GHSA-9jvj-xhwx-w88x","ROOT-OS-UBUNTU-2404-CVE-2025-39881","UBUNTU-CVE-2025-39881"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["code_execution","privilege_escalation"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel","requires_auth":"low_privilege","summary":"A use-after-free in the Linux kernel PSI monitoring allows local attackers to potentially execute code or escalate privileges via a race condition.","user_interaction":"not_required","vuln_class":"use_after_free"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[{"product":"debian_linux","vendor":"debian"},{"product":"linux_kernel","vendor":"linux"}],"cvss":{"score":7.8,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"cwes":[{"id":"CWE-416","name":"Use After Free"}],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nkernfs: Fix UAF in polling when open file is released\n\nA use-after-free (UAF) vulnerability was identified in the PSI (Pressure\nStall Information) monitoring mechanism:\n\nBUG: KASAN: slab-use-after-free in psi_trigger_poll+0x3c/0x140\nRead of size 8 at addr ffff3de3d50bd308 by task systemd/1\n\npsi_trigger_poll+0x3c/0x140\ncgroup_pressure_poll+0x70/0xa0\ncgroup_file_poll+0x8c/0x100\nkernfs_fop_poll+0x11c/0x1c0\nep_item_poll.isra.0+0x188/0x2c0\n\nAllocated by task 1:\ncgroup_file_open+0x88/0x388\nkernfs_fop_open+0x73c/0xaf0\ndo_dentry_open+0x5fc/0x1200\nvfs_open+0xa0/0x3f0\ndo_open+0x7e8/0xd08\npath_openat+0x2fc/0x6b0\ndo_filp_open+0x174/0x368\n\nFreed by task 8462:\ncgroup_file_release+0x130/0x1f8\nkernfs_drain_open_files+0x17c/0x440\nkernfs_drain+0x2dc/0x360\nkernfs_show+0x1b8/0x288\ncgroup_file_show+0x150/0x268\ncgroup_pressure_write+0x1dc/0x340\ncgroup_file_write+0x274/0x548\n\nReproduction Steps:\n1. Open test/cpu.pressure and establish epoll monitoring\n2. Disable monitoring: echo 0 \u003e test/cgroup.pressure\n3. Re-enable monitoring: echo 1 \u003e test/cgroup.pressure\n\nThe race condition occurs because:\n1. When cgroup.pressure is disabled (echo 0 \u003e cgroup.pressure), it:\n   - Releases PSI triggers via cgroup_file_release()\n   - Frees of-\u003epriv through kernfs_drain_open_files()\n2. While epoll still holds reference to the file and continues polling\n3. Re-enabling (echo 1 \u003e cgroup.pressure) accesses freed of-\u003epriv\n\nepolling\t\t\tdisable/enable cgroup.pressure\nfd=open(cpu.pressure)\nwhile(1)\n...\nepoll_wait\nkernfs_fop_poll\nkernfs_get_active = true\techo 0 \u003e cgroup.pressure\n...\t\t\t\tcgroup_file_show\n\t\t\t\tkernfs_show\n\t\t\t\t// inactive kn\n\t\t\t\tkernfs_drain_open_files\n\t\t\t\tcft-\u003erelease(of);\n\t\t\t\tkfree(ctx);\n\t\t\t\t...\nkernfs_get_active = false\n\t\t\t\techo 1 \u003e cgroup.pressure\n\t\t\t\tkernfs_show\n\t\t\t\tkernfs_activate_one(kn);\nkernfs_fop_poll\nkernfs_get_active = true\ncgroup_file_poll\npsi_trigger_poll\n// UAF\n...\nend: close(fd)\n\nTo address this issue, introduce kernfs_get_active_of() for kernfs open\nfiles to obtain active references. This function will fail if the open file\nhas been released. Replace kernfs_get_active() with kernfs_get_active_of()\nto prevent further operations on released file descriptors.","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":"kernfs: Fix UAF in polling when open file is released","id":"CVE-2025-39881","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"debian:debian_linux","products":["debian:debian_linux","linux:linux_kernel"],"type":"use_after_free","year":"2025"},"n_packages":0,"n_references":5,"next":{"headline":"drm/mediatek: fix potential OF node use-after-free","id":"CVE-2025-39882"},"packages":[],"prev":{"headline":"libceph: fix invalid accesses to ceph_connection_v1_info","id":"CVE-2025-39880"},"products":["Linux"],"published":"2025-09-23","related":[{"cvss_score":10,"headline":"ProFTPD Improper Access Control","id":"CVE-2015-3306","kev_date_added":"2026-10-08","published":"2015-05-18"},{"cvss_score":9.9,"headline":"RoundCube Webmail Deserialization of Untrusted Data","id":"CVE-2025-49113","kev_date_added":"2026-02-20","published":"2025-06-02"},{"cvss_score":9.8,"headline":"GNU InetUtils Argument Injection","id":"CVE-2026-24061","kev_date_added":"2026-01-26","published":"2026-01-21"},{"cvss_score":9.8,"headline":"Linux Kernel Improper Check for Unusual or Exceptional Conditions","id":"CVE-2025-39682","kev_date_added":"2026-09-18","published":"2025-09-05"},{"cvss_score":9.8,"headline":"Mozilla Firefox Use-After-Free","id":"CVE-2024-9680","kev_date_added":"2024-10-15","published":"2024-10-09"},{"cvss_score":9.8,"headline":"RARLAB UnRAR Directory Traversal","id":"CVE-2022-30333","kev_date_added":"2022-08-09","published":"2022-05-09"},{"cvss_score":9.8,"headline":"Roundcube Webmail SQL Injection","id":"CVE-2021-44026","kev_date_added":"2023-06-22","published":"2021-11-19"}],"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":"2026-08-05","vendors":["Linux"]},"summary":"A use-after-free in the Linux kernel PSI monitoring allows local attackers to potentially execute code or escalate privileges via a race condition.","url":"https://insights.sbomify.com/CVE-2025-39881/"}