{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2025-39879 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2025-39879 is a medium-severity vulnerability in Linux kernel, 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-2025-39879 and fix it if it is affected.\n\nWhat it is: CVE-2025-39879 is a medium-severity vulnerability in Linux kernel, 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-2025-39879 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-2025-39879/ (Markdown: https://insights.sbomify.com/CVE-2025-39879/index.md)","id":"CVE-2025-39879","markdown":"https://insights.sbomify.com/CVE-2025-39879/index.md","name":"CVE-2025-39879","record":{"aliases":["BELL-CVE-2025-39879","DEBIAN-CVE-2025-39879","GHSA-hq23-ggcp-mx5x","UBUNTU-CVE-2025-39879"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel Ceph client","requires_auth":"low_privilege","summary":"A logic error in the Linux kernel Ceph client causes NULL pointer dereferences, leading to kernel crashes and denial of service.","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\nceph: always call ceph_shift_unused_folios_left()\n\nThe function ceph_process_folio_batch() sets folio_batch entries to\nNULL, which is an illegal state.  Before folio_batch_release() crashes\ndue to this API violation, the function ceph_shift_unused_folios_left()\nis supposed to remove those NULLs from the array.\n\nHowever, since commit ce80b76dd327 (\"ceph: introduce\nceph_process_folio_batch() method\"), this shifting doesn't happen\nanymore because the \"for\" loop got moved to ceph_process_folio_batch(),\nand now the `i` variable that remains in ceph_writepages_start()\ndoesn't get incremented anymore, making the shifting effectively\nunreachable much of the time.\n\nLater, commit 1551ec61dc55 (\"ceph: introduce ceph_submit_write()\nmethod\") added more preconditions for doing the shift, replacing the\n`i` check (with something that is still just as broken):\n\n- if ceph_process_folio_batch() fails, shifting never happens\n\n- if ceph_move_dirty_page_in_page_array() was never called (because\n  ceph_process_folio_batch() has returned early for some of various\n  reasons), shifting never happens\n\n- if `processed_in_fbatch` is zero (because ceph_process_folio_batch()\n  has returned early for some of the reasons mentioned above or\n  because ceph_move_dirty_page_in_page_array() has failed), shifting\n  never happens\n\nSince those two commits, any problem in ceph_process_folio_batch()\ncould crash the kernel, e.g. this way:\n\n BUG: kernel NULL pointer dereference, address: 0000000000000034\n #PF: supervisor write access in kernel mode\n #PF: error_code(0x0002) - not-present page\n PGD 0 P4D 0\n Oops: Oops: 0002 [#1] SMP NOPTI\n CPU: 172 UID: 0 PID: 2342707 Comm: kworker/u778:8 Not tainted 6.15.10-cm4all1-es #714 NONE\n Hardware name: Dell Inc. PowerEdge R7615/0G9DHV, BIOS 1.6.10 12/08/2023\n Workqueue: writeback wb_workfn (flush-ceph-1)\n RIP: 0010:folios_put_refs+0x85/0x140\n Code: 83 c5 01 39 e8 7e 76 48 63 c5 49 8b 5c c4 08 b8 01 00 00 00 4d 85 ed 74 05 41 8b 44 ad 00 48 8b 15 b0 \u003e\n RSP: 0018:ffffb880af8db778 EFLAGS: 00010207\n RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000003\n RDX: ffffe377cc3b0000 RSI: 0000000000000000 RDI: ffffb880af8db8c0\n RBP: 0000000000000000 R08: 000000000000007d R09: 000000000102b86f\n R10: 0000000000000001 R11: 00000000000000ac R12: ffffb880af8db8c0\n R13: 0000000000000000 R14: 0000000000000000 R15: ffff9bd262c97000\n FS:  0000000000000000(0000) GS:ffff9c8efc303000(0000) knlGS:0000000000000000\n CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n CR2: 0000000000000034 CR3: 0000000160958004 CR4: 0000000000770ef0\n PKRU: 55555554\n Call Trace:\n  \u003cTASK\u003e\n  ceph_writepages_start+0xeb9/0x1410\n\nThe crash can be reproduced easily by changing the\nceph_check_page_before_write() return value to `-E2BIG`.\n\n(Interestingly, the crash happens only if `huge_zero_folio` has\nalready been allocated; without `huge_zero_folio`,\nis_huge_zero_folio(NULL) returns true and folios_put_refs() skips NULL\nentries instead of dereferencing them.  That makes reproducing the bug\nsomewhat unreliable.  See\nhttps://lore.kernel.org/20250826231626.218675-1-max.kellermann@ionos.com\nfor a discussion of this detail.)\n\nMy suggestion is to move the ceph_shift_unused_folios_left() to right\nafter ceph_process_folio_batch() to ensure it always gets called to\nfix up the illegal folio_batch state.","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":"ceph: always call ceph_shift_unused_folios_left()","id":"CVE-2025-39879","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":"libceph: fix invalid accesses to ceph_connection_v1_info","id":"CVE-2025-39880"},"packages":[],"prev":{"headline":"ceph: fix crash after fscrypt_encrypt_pagecache_blocks() error","id":"CVE-2025-39878"},"products":["Linux"],"published":"2025-09-23","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":"2026-10-21","vendors":["Linux"]},"summary":"A logic error in the Linux kernel Ceph client causes NULL pointer dereferences, leading to kernel crashes and denial of service.","url":"https://insights.sbomify.com/CVE-2025-39879/"}