{"id":"AZL-75126","summary":"CVE-2025-71160 affecting package kernel for versions less than 6.6.121.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_tables: avoid chain re-validation if possible\n\nHamza Mahfooz reports cpu soft lock-ups in\nnft_chain_validate():\n\n watchdog: BUG: soft lockup - CPU#1 stuck for 27s! [iptables-nft-re:37547]\n[..]\n RIP: 0010:nft_chain_validate+0xcb/0x110 [nf_tables]\n[..]\n  nft_immediate_validate+0x36/0x50 [nf_tables]\n  nft_chain_validate+0xc9/0x110 [nf_tables]\n  nft_immediate_validate+0x36/0x50 [nf_tables]\n  nft_chain_validate+0xc9/0x110 [nf_tables]\n  nft_immediate_validate+0x36/0x50 [nf_tables]\n  nft_chain_validate+0xc9/0x110 [nf_tables]\n  nft_immediate_validate+0x36/0x50 [nf_tables]\n  nft_chain_validate+0xc9/0x110 [nf_tables]\n  nft_immediate_validate+0x36/0x50 [nf_tables]\n  nft_chain_validate+0xc9/0x110 [nf_tables]\n  nft_immediate_validate+0x36/0x50 [nf_tables]\n  nft_chain_validate+0xc9/0x110 [nf_tables]\n  nft_table_validate+0x6b/0xb0 [nf_tables]\n  nf_tables_validate+0x8b/0xa0 [nf_tables]\n  nf_tables_commit+0x1df/0x1eb0 [nf_tables]\n[..]\n\nCurrently nf_tables will traverse the entire table (chain graph), starting\nfrom the entry points (base chains), exploring all possible paths\n(chain jumps).  But there are cases where we could avoid revalidation.\n\nConsider:\n1  input -\u003e j2 -\u003e j3\n2  input -\u003e j2 -\u003e j3\n3  input -\u003e j1 -\u003e j2 -\u003e j3\n\nThen the second rule does not need to revalidate j2, and, by extension j3,\nbecause this was already checked during validation of the first rule.\nWe need to validate it only for rule 3.\n\nThis is needed because chain loop detection also ensures we do not exceed\nthe jump stack: Just because we know that j2 is cycle free, its last jump\nmight now exceed the allowed stack size.  We also need to update all\nreachable chains with the new largest observed call depth.\n\nCare has to be taken to revalidate even if the chain depth won't be an\nissue: chain validation also ensures that expressions are not called from\ninvalid base chains.  For example, the masquerade expression can only be\ncalled from NAT postrouting base chains.\n\nTherefore we also need to keep record of the base chain context (type,\nhooknum) and revalidate if the chain becomes reachable from a different\nhook location.","modified":"2026-04-21T04:38:51.772276Z","published":"2026-01-23T16:15:52Z","upstream":["CVE-2025-71160"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-71160"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.121.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-75126.json"}}],"schema_version":"1.7.5"}