{"id":"CVE-2023-53186","state":"PUBLISHED","title":"skbuff: Fix a race between coalescing and releasing SKBs","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nskbuff: Fix a race between coalescing and releasing SKBs\n\nCommit 1effe8ca4e34 (\"skbuff: fix coalescing for page_pool fragment\nrecycling\") allowed coalescing to proceed with non page pool page and page\npool page when @from is cloned, i.e.\n\nto->pp_recycle    --> false\nfrom->pp_recycle  --> true\nskb_cloned(from)  --> true\n\nHowever, it actually requires skb_cloned(@from) to hold true until\ncoalescing finishes in this situation. If the other cloned SKB is\nreleased while the merging is in process, from_shinfo->nr_frags will be\nset to 0 toward the end of the function, causing the increment of frag\npage _refcount to be unexpectedly skipped resulting in inconsistent\nreference counts. Later when SKB(@to) is released, it frees the page\ndirectly even though the page pool page is still in use, leading to\nuse-after-free or double-free errors. So it should be prohibited.\n\nThe double-free error message below prompted us to investigate:\nBUG: Bad page state in process swapper/1  pfn:0e0d1\npage:00000000c6548b28 refcount:-1 mapcount:0 mapping:0000000000000000\nindex:0x2 pfn:0xe0d1\nflags: 0xfffffc0000000(node=0|zone=1|lastcpupid=0x1fffff)\nraw: 000fffffc0000000 0000000000000000 ffffffff00000101 0000000000000000\nraw: 0000000000000002 0000000000000000 ffffffffffffffff 0000000000000000\npage dumped because: nonzero _refcount\n\nCPU: 1 PID: 0 Comm: swapper/1 Tainted: G            E      6.2.0+\nCall Trace:\n <IRQ>\ndump_stack_lvl+0x32/0x50\nbad_page+0x69/0xf0\nfree_pcp_prepare+0x260/0x2f0\nfree_unref_page+0x20/0x1c0\nskb_release_data+0x10b/0x1a0\nnapi_consume_skb+0x56/0x150\nnet_rx_action+0xf0/0x350\n? __napi_schedule+0x79/0x90\n__do_softirq+0xc8/0x2b1\n__irq_exit_rcu+0xb9/0xf0\ncommon_interrupt+0x82/0xa0\n</IRQ>\n<TASK>\nasm_common_interrupt+0x22/0x40\nRIP: 0010:default_idle+0xb/0x20","publishedAt":"2025-09-15T14:04:38.954Z","updatedAt":"2026-10-15T21:41:27.688Z","severity":{"score":8.1,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"53e0961da1c7bbdabd1abebb20de403ec237ec09","status":"affected","lessThan":"906a6689bb0191ad2a44131a3377006aa098af59","versionType":"git"},{"version":"53e0961da1c7bbdabd1abebb20de403ec237ec09","status":"affected","lessThan":"71850b5af92da21b4862a9bc55bda61091247d00","versionType":"git"},{"version":"53e0961da1c7bbdabd1abebb20de403ec237ec09","status":"affected","lessThan":"5f692c992a3bb9a8018e3488098b401a4229e7ec","versionType":"git"},{"version":"53e0961da1c7bbdabd1abebb20de403ec237ec09","status":"affected","lessThan":"0646dc31ca886693274df5749cd0c8c1eaaeb5ca","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/core/skbuff.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.15","versionType":"semver"},{"version":"5.15.108","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.25","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.2.12","status":"unaffected","lessThanOrEqual":"6.2.*","versionType":"semver"},{"version":"6.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/core/skbuff.c"]}],"references":["https://git.kernel.org/stable/c/906a6689bb0191ad2a44131a3377006aa098af59","https://git.kernel.org/stable/c/71850b5af92da21b4862a9bc55bda61091247d00","https://git.kernel.org/stable/c/5f692c992a3bb9a8018e3488098b401a4229e7ec","https://git.kernel.org/stable/c/0646dc31ca886693274df5749cd0c8c1eaaeb5ca"],"weaknesses":[],"ingestedAt":"2026-10-29T20:06:33.064Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2023/53xxx/CVE-2023-53186.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2023-53186","state":"PUBLISHED","datePublished":"2025-09-15T14:04:38.954Z","dateUpdated":"2026-10-15T21:41:27.688Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-09-15T13:59:19.066Z"},"containers":{"cna":{"title":"skbuff: Fix a race between coalescing and releasing SKBs","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nskbuff: Fix a race between coalescing and releasing SKBs\n\nCommit 1effe8ca4e34 (\"skbuff: fix coalescing for page_pool fragment\nrecycling\") allowed coalescing to proceed with non page pool page and page\npool page when @from is cloned, i.e.\n\nto->pp_recycle    --> false\nfrom->pp_recycle  --> true\nskb_cloned(from)  --> true\n\nHowever, it actually requires skb_cloned(@from) to hold true until\ncoalescing finishes in this situation. If the other cloned SKB is\nreleased while the merging is in process, from_shinfo->nr_frags will be\nset to 0 toward the end of the function, causing the increment of frag\npage _refcount to be unexpectedly skipped resulting in inconsistent\nreference counts. Later when SKB(@to) is released, it frees the page\ndirectly even though the page pool page is still in use, leading to\nuse-after-free or double-free errors. So it should be prohibited.\n\nThe double-free error message below prompted us to investigate:\nBUG: Bad page state in process swapper/1  pfn:0e0d1\npage:00000000c6548b28 refcount:-1 mapcount:0 mapping:0000000000000000\nindex:0x2 pfn:0xe0d1\nflags: 0xfffffc0000000(node=0|zone=1|lastcpupid=0x1fffff)\nraw: 000fffffc0000000 0000000000000000 ffffffff00000101 0000000000000000\nraw: 0000000000000002 0000000000000000 ffffffffffffffff 0000000000000000\npage dumped because: nonzero _refcount\n\nCPU: 1 PID: 0 Comm: swapper/1 Tainted: G            E      6.2.0+\nCall Trace:\n <IRQ>\ndump_stack_lvl+0x32/0x50\nbad_page+0x69/0xf0\nfree_pcp_prepare+0x260/0x2f0\nfree_unref_page+0x20/0x1c0\nskb_release_data+0x10b/0x1a0\nnapi_consume_skb+0x56/0x150\nnet_rx_action+0xf0/0x350\n? __napi_schedule+0x79/0x90\n__do_softirq+0xc8/0x2b1\n__irq_exit_rcu+0xb9/0xf0\ncommon_interrupt+0x82/0xa0\n</IRQ>\n<TASK>\nasm_common_interrupt+0x22/0x40\nRIP: 0010:default_idle+0xb/0x20"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"53e0961da1c7bbdabd1abebb20de403ec237ec09","status":"affected","lessThan":"906a6689bb0191ad2a44131a3377006aa098af59","versionType":"git"},{"version":"53e0961da1c7bbdabd1abebb20de403ec237ec09","status":"affected","lessThan":"71850b5af92da21b4862a9bc55bda61091247d00","versionType":"git"},{"version":"53e0961da1c7bbdabd1abebb20de403ec237ec09","status":"affected","lessThan":"5f692c992a3bb9a8018e3488098b401a4229e7ec","versionType":"git"},{"version":"53e0961da1c7bbdabd1abebb20de403ec237ec09","status":"affected","lessThan":"0646dc31ca886693274df5749cd0c8c1eaaeb5ca","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/core/skbuff.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.15","versionType":"semver"},{"version":"5.15.108","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.25","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.2.12","status":"unaffected","lessThanOrEqual":"6.2.*","versionType":"semver"},{"version":"6.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/core/skbuff.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/906a6689bb0191ad2a44131a3377006aa098af59"},{"url":"https://git.kernel.org/stable/c/71850b5af92da21b4862a9bc55bda61091247d00"},{"url":"https://git.kernel.org/stable/c/5f692c992a3bb9a8018e3488098b401a4229e7ec"},{"url":"https://git.kernel.org/stable/c/0646dc31ca886693274df5749cd0c8c1eaaeb5ca"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":8.1,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - skb_try_coalesce() is reached from the TCP receive path (tcp_try_coalesce/tcp_queue_rcv) and IP defrag while processing inbound packets on page_pool NICs; a remote peer sending TCP segments to a listening service drives the vulnerable coalesce without local code execution.\nAC:H - The bug is a TOCTOU on skb_cloned(from) between the pp_recycle admission check and the later nr_frags/__skb_frag_ref logic; winning it requires a sibling clone (typically from AF_PACKET/monitoring or bridge fanout) to be released on another CPU during that window, which a pure remote sender cannot fully control.\nPR:N - Exploitation uses unauthenticated network traffic to an already-exposed TCP/IP service; packet taps or bridging that create clones are victim-side deployment state, not credentials or capabilities the attacker must hold on the host.\nUI:N - Coalescing runs in softirq/NAPI receive context on packet arrival; no user action such as mounting, opening a file, or confirming a prompt is required.\nS:U - The resulting page use-after-free/double-free corrupts host kernel memory within the same OS authority; it is not a VM escape, IOMMU bypass, or sandbox boundary cross.\nC:H - The race skips __skb_frag_ref while still attaching frags to @to, then frees page_pool pages still in use—classic page UAF that can be groomed for arbitrary kernel memory disclosure.\nI:H - The same UAF/double-free of page_pool pages yields heap aliasing and write primitives suitable for control-flow hijacking, matching kernel guidance that exploitable UAF is Integrity High.\nA:H - The fix commit documents a reproducible BUG/bad-page-state crash in skb_release_data→free_unref_page from net_rx softirq, so availability impact is a full kernel oops/panic."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T09:13:00.022Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"5.15.108"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.1.25"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.2.12"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2023-53186","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-15T21:34:19.294430Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-15T21:41:27.688Z"}}]}}}