{ "schema_version": "1.6.1", "id": "RPI-CVE-2025-21893", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2025-21893" ], "published": "2025-03-31T19:45:04Z", "summary": "keys: Fix UAF in key_put()", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nkeys: Fix UAF in key_put()\n\nOnce a key's reference count has been reduced to 0, the garbage collector\nthread may destroy it at any time and so key_put() is not allowed to touch\nthe key after that point. The most key_put() is normally allowed to do is\nto touch key_gc_work as that's a static global variable.\n\nHowever, in an effort to speed up the reclamation of quota, this is now\ndone in key_put() once the key's usage is reduced to 0 - but now the code\nis looking at the key after the deadline, which is forbidden.\n\nFix this by using a flag to indicate that a key can be gc'd now rather than\nlooking at the key's refcount in the garbage collector.", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:12", "name": "linux" }, "versions": [ "1:6.12.20-1+rpt1~bpo12+1" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.12.20+rpt-rpi-2712", "binary_version": "1:6.12.20-1+rpt1~bpo12+1" }, { "binary_name": "linux-image-6.12.20+rpt-rpi-v6", "binary_version": "1:6.12.20-1+rpt1~bpo12+1" }, { "binary_name": "linux-image-6.12.20+rpt-rpi-v7", "binary_version": "1:6.12.20-1+rpt1~bpo12+1" }, { "binary_name": "linux-image-6.12.20+rpt-rpi-v7l", "binary_version": "1:6.12.20-1+rpt1~bpo12+1" }, { "binary_name": "linux-image-6.12.20+rpt-rpi-v8", "binary_version": "1:6.12.20-1+rpt1~bpo12+1" } ] }, "database_specific": { "per_version": { "1:6.12.20-1+rpt1~bpo12+1": { "linux_commit": "cd231d4775b14f228606c09f219b48308f6ab3aa", "upstream_version": "6.12.20", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.12.21" } } } }, { "package": { "ecosystem": "Raspberry Pi OS:13", "name": "linux" }, "versions": [ "1:6.12.19-1+rpt1~bpo12+1", "1:6.12.19-1+rpt1", "1:6.12.20-1+rpt1" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.12.19+rpt-rpi-2712", "binary_version": "1:6.12.19-1+rpt1~bpo12+1" }, { "binary_name": "linux-image-6.12.19+rpt-rpi-v6", "binary_version": "1:6.12.19-1+rpt1~bpo12+1" }, { "binary_name": "linux-image-6.12.19+rpt-rpi-v7", "binary_version": "1:6.12.19-1+rpt1~bpo12+1" }, { "binary_name": "linux-image-6.12.19+rpt-rpi-v7l", "binary_version": "1:6.12.19-1+rpt1~bpo12+1" }, { "binary_name": "linux-image-6.12.19+rpt-rpi-v8", "binary_version": "1:6.12.19-1+rpt1~bpo12+1" }, { "binary_name": "linux-image-6.12.19+rpt-rpi-2712", "binary_version": "1:6.12.19-1+rpt1" }, { "binary_name": "linux-image-6.12.19+rpt-rpi-v6", "binary_version": "1:6.12.19-1+rpt1" }, { "binary_name": "linux-image-6.12.19+rpt-rpi-v7", "binary_version": "1:6.12.19-1+rpt1" }, { "binary_name": "linux-image-6.12.19+rpt-rpi-v7l", "binary_version": "1:6.12.19-1+rpt1" }, { "binary_name": "linux-image-6.12.19+rpt-rpi-v8", "binary_version": "1:6.12.19-1+rpt1" }, { "binary_name": "linux-image-6.12.20+rpt-rpi-2712", "binary_version": "1:6.12.20-1+rpt1" }, { "binary_name": "linux-image-6.12.20+rpt-rpi-v6", "binary_version": "1:6.12.20-1+rpt1" }, { "binary_name": "linux-image-6.12.20+rpt-rpi-v7", "binary_version": "1:6.12.20-1+rpt1" }, { "binary_name": "linux-image-6.12.20+rpt-rpi-v7l", "binary_version": "1:6.12.20-1+rpt1" }, { "binary_name": "linux-image-6.12.20+rpt-rpi-v8", "binary_version": "1:6.12.20-1+rpt1" } ] }, "database_specific": { "per_version": { "1:6.12.19-1+rpt1~bpo12+1": { "linux_commit": "121c2c384b9c2f4790ffb31b2cd25c7d75c8fda0", "upstream_version": "6.12.19", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.12.21" }, "1:6.12.19-1+rpt1": { "linux_commit": "121c2c384b9c2f4790ffb31b2cd25c7d75c8fda0", "upstream_version": "6.12.19", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.12.21" }, "1:6.12.20-1+rpt1": { "linux_commit": "cd231d4775b14f228606c09f219b48308f6ab3aa", "upstream_version": "6.12.20", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.12.21" } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2025-21893" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/6afe2ea2daec156bd94ad2c5a6f4f4c48240dcd3" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/f6a3cf833188e897c97028cd7b926e3f2cb1a8c0" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/75845c6c1a64483e9985302793dbf0dfa5f71e32" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-08-05T12:19:11Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 7.8, "cvss_v3_severity": "High", "scenario": "AV:L - The keyrings code is reached only through local syscalls (add_key, request_key, keyctl); there is no network-facing path to key_put().\nAC:L - It is a race, but the attacker controls both sides \u2014 invoking key_put() by dropping references while driving GC via key churn/expiry \u2014 and the operation is freely repeatable until the window is won (syzbot reproduced it).\nPR:L - Any unprivileged local user can create and drop keys via the keyrings syscalls; no capabilities or root are required.\nUI:N - The race is triggered entirely by the attacker's own syscalls with no victim action needed.\nS:U - The vulnerability and its impact are contained within the kernel's own security authority with no crossing of a boundary such as VM/IOMMU.\nC:H - The UAF dereferences a freed key and its freed key_user pointer, allowing attacker-controlled reallocated contents to be read \u2014 arbitrary-read class disclosure.\nI:H - key_put() writes into the freed object (spinlock ops and qnkeys/qnbytes decrements through key->user), giving a heap-sprayable write primitive over reclaimed memory.\nA:H - A use-after-free reliably causes kernel oops/panic and slab corruption when the race is won." } } }