{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-23274", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-01-13T15:37:45.991Z", "datePublished": "2026-03-20T08:08:54.918Z", "dateUpdated": "2026-08-05T12:21:04.973Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:21:04.973Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: xt_IDLETIMER: reject rev0 reuse of ALARM timer labels\n\nIDLETIMER revision 0 rules reuse existing timers by label and always call\nmod_timer() on timer->timer.\n\nIf the label was created first by revision 1 with XT_IDLETIMER_ALARM,\nthe object uses alarm timer semantics and timer->timer is never initialized.\nReusing that object from revision 0 causes mod_timer() on an uninitialized\ntimer_list, triggering debugobjects warnings and possible panic when\npanic_on_warn=1.\n\nFix this by rejecting revision 0 rule insertion when an existing timer with\nthe same label is of ALARM type." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - This is accessed through the iptables/netfilter sockopt interface (IPT_SO_SET_REPLACE), which requires local system access to create iptables rules. This is a local attack vector via setsockopt syscall.\nAC:L - The attacker can reliably trigger this by first creating a rev1 IDLETIMER rule with XT_IDLETIMER_ALARM flag and a chosen label, then creating a rev0 rule with the same label. No race condition or special conditions needed — this is a deterministic two-step operation.\nPR:L - The iptables interface requires CAP_NET_ADMIN, but ip_tables.c uses ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN), meaning an unprivileged user can obtain this capability via user namespaces (unshare -Urn), making this reachable from a low-privilege user.\nUI:N - No user interaction is required. The attacker creates both iptables rules themselves without any victim action.\nS:U - The vulnerability stays within the kernel's security scope — there is no crossing of a security boundary like VM escape or sandbox escape. It's a standard kernel privilege escalation scenario.\nC:H - The bug calls mod_timer() on an uninitialized timer_list from kmalloc'd memory. Since kmalloc does not zero memory, the timer_list contains stale heap content which an attacker can influence via heap spraying, potentially achieving arbitrary read through controlled function pointers and timer wheel manipulation.\nI:H - Operating mod_timer() on a timer_list with attacker-influenced stale heap data (uninitialized function pointer, hlist_node entries) can corrupt timer wheel data structures and potentially achieve arbitrary code execution if the function pointer is controlled through heap spraying.\nA:H - At minimum, mod_timer() on uninitialized memory triggers debug_assert_init() WARN which causes panic with panic_on_warn=1. Even without that, following garbage pointers in timer_list->entry corrupts kernel data structures causing a crash/oops." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/netfilter/xt_IDLETIMER.c" ], "versions": [ { "version": "68983a354a655c35d3fb204489d383a2a051fda7", "lessThan": "32e937dc6e97f5ed3cdfe3fc0b2b19a05e23fa44", "status": "affected", "versionType": "git" }, { "version": "68983a354a655c35d3fb204489d383a2a051fda7", "lessThan": "144f88054ba0180467356f40895bd660b5dceeec", "status": "affected", "versionType": "git" }, { "version": "68983a354a655c35d3fb204489d383a2a051fda7", "lessThan": "28c7cfaf0c0ab17cbd7754092116fd1af45271f9", "status": "affected", "versionType": "git" }, { "version": "68983a354a655c35d3fb204489d383a2a051fda7", "lessThan": "54080355999381fed4a26129579a5765bab87491", "status": "affected", "versionType": "git" }, { "version": "68983a354a655c35d3fb204489d383a2a051fda7", "lessThan": "5e7ece24c5cb75a60402aad4d803c7898ea40aa9", "status": "affected", "versionType": "git" }, { "version": "68983a354a655c35d3fb204489d383a2a051fda7", "lessThan": "f5ef97c13165542480a6ffdbe6f09f40bbb7cbf1", "status": "affected", "versionType": "git" }, { "version": "68983a354a655c35d3fb204489d383a2a051fda7", "lessThan": "f228b9ae2a7e84d1153616d8e71c4236cb1f1309", "status": "affected", "versionType": "git" }, { "version": "68983a354a655c35d3fb204489d383a2a051fda7", "lessThan": "329f0b9b48ee6ab59d1ab72fef55fe8c6463a6cf", "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/xt_IDLETIMER.c" ], "versions": [ { "version": "5.7", "status": "affected" }, { "version": "0", "lessThan": "5.7", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.253", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.203", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.167", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.130", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.78", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.19", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.19.9", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0", "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": "5.7", "versionEndExcluding": "5.10.253" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.7", "versionEndExcluding": "5.15.203" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.7", "versionEndExcluding": "6.1.167" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.7", "versionEndExcluding": "6.6.130" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.7", "versionEndExcluding": "6.12.78" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.7", "versionEndExcluding": "6.18.19" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.7", "versionEndExcluding": "6.19.9" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.7", "versionEndExcluding": "7.0" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/32e937dc6e97f5ed3cdfe3fc0b2b19a05e23fa44" }, { "url": "https://git.kernel.org/stable/c/144f88054ba0180467356f40895bd660b5dceeec" }, { "url": "https://git.kernel.org/stable/c/28c7cfaf0c0ab17cbd7754092116fd1af45271f9" }, { "url": "https://git.kernel.org/stable/c/54080355999381fed4a26129579a5765bab87491" }, { "url": "https://git.kernel.org/stable/c/5e7ece24c5cb75a60402aad4d803c7898ea40aa9" }, { "url": "https://git.kernel.org/stable/c/f5ef97c13165542480a6ffdbe6f09f40bbb7cbf1" }, { "url": "https://git.kernel.org/stable/c/f228b9ae2a7e84d1153616d8e71c4236cb1f1309" }, { "url": "https://git.kernel.org/stable/c/329f0b9b48ee6ab59d1ab72fef55fe8c6463a6cf" } ], "title": "netfilter: xt_IDLETIMER: reject rev0 reuse of ALARM timer labels", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "x_adpType": "supplier", "providerMetadata": { "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e", "shortName": "siemens-SADP", "dateUpdated": "2026-07-14T12:46:21.453Z" }, "affected": [ { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.5", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.5", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": 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