{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-72020", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-09T03:40:39.900Z", "datePublished": "2026-08-15T05:51:46.675Z", "dateUpdated": "2026-10-19T21:19:23.243Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T05:39:30.496Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipvs: reset full ip_vs_seq structs in ip_vs_conn_new\n\nCommit 9a05475cebdd (\"ipvs: avoid kmem_cache_zalloc in\nip_vs_conn_new\") changed ip_vs_conn_new() to allocate an ip_vs_conn\nobject with kmem_cache_alloc(). The function then initializes many\nfields explicitly, but only resets in_seq.delta and out_seq.delta in the\ntwo struct ip_vs_seq members.\n\nThat leaves init_seq and previous_delta uninitialized. This is normally\nharmless while the corresponding IP_VS_CONN_F_IN_SEQ or\nIP_VS_CONN_F_OUT_SEQ flag is clear. For connections learned from a sync\nmessage, however, ip_vs_proc_conn() preserves those flags from\nIP_VS_CONN_F_BACKUP_MASK and passes opt=NULL when the message omits\nIPVS_OPT_SEQ_DATA. In that case the new connection can be hashed with\nSEQ flags set but with the rest of in_seq/out_seq still containing stale\nslab data.\n\nWhen a packet for such a connection is later handled by an IPVS\napplication helper, vs_fix_seq() and vs_fix_ack_seq() use\nprevious_delta and init_seq to rewrite TCP sequence numbers. A malformed\nsync message can therefore make forwarded packets carry stale slab bytes\nin their TCP seq/ack numbers, and can also corrupt the forwarded TCP\nflow.\n\nReset both struct ip_vs_seq members completely before publishing the\nconnection. This matches the existing \"reset struct ip_vs_seq\" comment\nand keeps the sequence-adjustment gates inactive unless valid sequence\ndata is installed later." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - The bug is reached when a host running the IPVS backup sync receiver processes forged UDP sync datagrams (default multicast 224.0.0.81:8848) in ip_vs_process_message(), which is a network packet receive path rather than a local-only ioctl/netlink interface.\nAC:L - Once IPVS backup sync is enabled, an attacker can reliably send IPVS v1 messages that set IP_VS_CONN_F_IN_SEQ/OUT_SEQ while omitting IPVS_OPT_SEQ_DATA; no race, heap grooming, or victim-specific state beyond matching syncid (often 0) is required.\nPR:N - The backup sync socket accepts unauthenticated UDP input with no capability checks; only an optional syncid filter (frequently left at 0) may drop messages, so the attacker needs no Linux privileges to inject the malformed sync records.\nUI:N - No end-user or administrator interaction is required at exploit time; the attacker directly delivers crafted sync messages to the listening backup daemon without victims opening files, clicking links, or changing settings.\nS:U - Exploitation stays within the IPVS load balancer kernel/network authority and affects connections it forwards; it does not constitute a VM escape, sandbox breakout, or cross-security-authority boundary such as guest-to-host.\nC:H - Uninitialized ip_vs_seq init_seq and previous_delta fields retain stale slab data that vs_fix_seq()/vs_fix_ack_seq() apply when rewriting forwarded TCP seq/ack numbers, leaking kernel heap bytes onto the network to clients or backend servers.\nI:H - Those same uninitialized sequence-adjustment fields cause incorrect TCP sequence/ack rewriting in NAT/application-helper paths (ip_vs_app_pkt_in/out), corrupting load-balanced TCP flows and enabling attacker-driven manipulation of forwarded traffic integrity.\nA:H - Corrupted TCP sequence handling breaks or resets connections on the virtual service and can be triggered repeatedly via additional forged sync messages, causing sustained denial of service to load-balanced traffic on the affected backup node." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/netfilter/ipvs/ip_vs_conn.c" ], "versions": [ { "version": "9a05475cebdd6341884b5901e53870be26e65158", "lessThan": "3bf9a260188b2a5449cbddc032a749ab433fe328", "status": "affected", "versionType": "git" }, { "version": "9a05475cebdd6341884b5901e53870be26e65158", "lessThan": "6378c5cb360eb1750f88839d7c3613ea92ac1816", "status": "affected", "versionType": "git" }, { "version": "9a05475cebdd6341884b5901e53870be26e65158", "lessThan": "32c299e28b8eea6cbbd23b97dc61401e9ef9c445", "status": "affected", "versionType": "git" }, { "version": "9a05475cebdd6341884b5901e53870be26e65158", "lessThan": "9e36602cbec552286f7e691cfd366525c565ee74", "status": "affected", "versionType": "git" }, { "version": "9a05475cebdd6341884b5901e53870be26e65158", "lessThan": "d0eed7177e822cab83141e5c44b2aa345c7fd379", "status": "affected", "versionType": "git" }, { "version": "9a05475cebdd6341884b5901e53870be26e65158", "lessThan": "83fb4c2c5344f02eac929f66de3c9d1adfcde04c", "status": "affected", "versionType": "git" }, { "version": "9a05475cebdd6341884b5901e53870be26e65158", "lessThan": "6335ab62d5fc9ed875279238233fba3462c168f5", "status": "affected", "versionType": "git" }, { "version": "9a05475cebdd6341884b5901e53870be26e65158", "lessThan": "2975324d164c552b028632f107b567302863b7f6", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/netfilter/ipvs/ip_vs_conn.c" ], "versions": [ { "version": "3.10", "status": "affected" }, { "version": "0", "lessThan": "3.10", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.261", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.212", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.178", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.145", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.97", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.40", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.5", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "5.10.261" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "5.15.212" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "6.1.178" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "6.6.145" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "6.12.97" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "6.18.40" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "7.1.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.10", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/3bf9a260188b2a5449cbddc032a749ab433fe328" }, { "url": "https://git.kernel.org/stable/c/6378c5cb360eb1750f88839d7c3613ea92ac1816" }, { "url": "https://git.kernel.org/stable/c/32c299e28b8eea6cbbd23b97dc61401e9ef9c445" }, { "url": "https://git.kernel.org/stable/c/9e36602cbec552286f7e691cfd366525c565ee74" }, { "url": "https://git.kernel.org/stable/c/d0eed7177e822cab83141e5c44b2aa345c7fd379" }, { "url": "https://git.kernel.org/stable/c/83fb4c2c5344f02eac929f66de3c9d1adfcde04c" }, { "url": "https://git.kernel.org/stable/c/6335ab62d5fc9ed875279238233fba3462c168f5" }, { "url": "https://git.kernel.org/stable/c/2975324d164c552b028632f107b567302863b7f6" } ], "title": "ipvs: reset full ip_vs_seq structs in ip_vs_conn_new", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2026-72020", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "yes" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2026-10-16T15:50:08.361059Z" } } } ], "problemTypes": [ { "descriptions": [ { "lang": "en", "type": "CWE", "cweId": "CWE-457", "description": "CWE-457 Use of Uninitialized Variable" } ] } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-19T21:19:23.243Z" } } ] } }