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CVE-2026-68415 (GCVE-0-2026-68415)

Vulnerability from cvelistv5 – Published: 2026-08-10 12:04 – Updated: 2026-08-17 05:05
VLAI
Title
xfrm: clear mode callbacks after failed mode setup
Summary
In the Linux kernel, the following vulnerability has been resolved: xfrm: clear mode callbacks after failed mode setup xfrm_state_gc_task can run long after a failed IPTFS state setup. In the reproduced case, __xfrm_init_state() cached x->mode_cbs, IPTFS setup returned -ENOMEM before publishing mode_data, and the temporary module reference from xfrm_get_mode_cbs() was dropped immediately. The dead state then kept x->mode_cbs until deferred GC ran after xfrm_iptfs had been unloaded. Clear x->mode_cbs when mode init or clone fails before publishing mode_data. Those states never installed mode-specific state or the long-term IPTFS module pin, so deferred GC has nothing mode-specific to destroy and must not retain a callback table pointer past the temporary lookup reference. The buggy scenario involves two paths, with each column showing the order within that path: failed setup path: 1. cache x->mode_cbs 2. mode setup fails before mode_data 3. drop the temporary module ref 4. dead state keeps x->mode_cbs cached GC/unload path: 1. xfrm_state_put() queues GC work 2. xfrm_iptfs unloads later 3. xfrm_state_gc_task runs 4. GC dereferences stale x->mode_cbs This also covers the failed clone path where clone_state() returns before publishing mode_data. Validation reproduced this kernel report: Kernel panic - not syncing: Fatal exception CONFIG_FAULT_INJECTION_STACKTRACE_FILTER=y failslab_stacktrace_filter matched xfrm_iptfs frames ack_error=-12 FAULT_INJECTION: forcing a failure BUG: unable to handle page fault Workqueue: events xfrm_state_gc_task RIP: xfrm_state_gc_task+0x142/0x650 Modules linked in: esp4_offload xfrm_user [last unloaded: xfrm_iptfs] Kernel panic - not syncing: Fatal exception
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 4b3faf610cc63bfac972711635eafbca5e7d7117 , < 9845a35986a658816f7752f7ebd7c455a4c7dfdf (git)
Affected: 4b3faf610cc63bfac972711635eafbca5e7d7117 , < c37a079230128a5237f45fb4e181bc069a5c2955 (git)
Affected: 4b3faf610cc63bfac972711635eafbca5e7d7117 , < 2538bd3cd1ff5af655908469544ac7b7ae259386 (git)
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Linux Linux Affected: 6.14
Unaffected: 0 , < 6.14 (semver)
Unaffected: 6.18.42 , ≤ 6.18.* (semver)
Unaffected: 7.1.6 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/xfrm/xfrm_state.c"
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          "vendor": "Linux",
          "versions": [
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              "versionType": "semver"
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                  "vulnerable": true
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: clear mode callbacks after failed mode setup\n\nxfrm_state_gc_task can run long after a failed IPTFS state setup. In the\nreproduced case, __xfrm_init_state() cached x-\u003emode_cbs, IPTFS setup\nreturned -ENOMEM before publishing mode_data, and the temporary module\nreference from xfrm_get_mode_cbs() was dropped immediately. The dead state\nthen kept x-\u003emode_cbs until deferred GC ran after xfrm_iptfs had been\nunloaded.\n\nClear x-\u003emode_cbs when mode init or clone fails before publishing\nmode_data. Those states never installed mode-specific state or the\nlong-term IPTFS module pin, so deferred GC has nothing mode-specific to\ndestroy and must not retain a callback table pointer past the temporary\nlookup reference.\n\nThe buggy scenario involves two paths, with each column showing the order\nwithin that path:\n\nfailed setup path:\n1. cache x-\u003emode_cbs\n2. mode setup fails before mode_data\n3. drop the temporary module ref\n4. dead state keeps x-\u003emode_cbs cached\n\nGC/unload path:\n1. xfrm_state_put() queues GC work\n2. xfrm_iptfs unloads later\n3. xfrm_state_gc_task runs\n4. GC dereferences stale x-\u003emode_cbs\n\nThis also covers the failed clone path where clone_state() returns before\npublishing mode_data.\n\nValidation reproduced this kernel report:\nKernel panic - not syncing: Fatal exception\nCONFIG_FAULT_INJECTION_STACKTRACE_FILTER=y\nfailslab_stacktrace_filter matched xfrm_iptfs frames\nack_error=-12\nFAULT_INJECTION: forcing a failure\nBUG: unable to handle page fault\nWorkqueue: events xfrm_state_gc_task\nRIP: xfrm_state_gc_task+0x142/0x650\nModules linked in: esp4_offload xfrm_user [last unloaded: xfrm_iptfs]\nKernel panic - not syncing: Fatal exception"
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            "version": "3.1"
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              "value": "AV:L - The vulnerable paths are reached only through the XFRM configuration interface \u2014 netlink XFRM_MSG_NEWSA/XFRM_MSG_MIGRATE handled by xfrm_user.c \u2014 which requires a local socket on the machine; no remote peer data reaches this code.\nAC:L - The attacker fully controls SA creation and the failing allocation size (XFRMA_IPTFS_REORDER_WINDOW up to 65535 slots, ~1MB order-8 kmalloc), so the -ENOMEM setup failure is attacker-inducible and repeatable, and unlimited poisoned dead states can be armed so the stale x-\u003emode_cbs dereference in xfrm_state_gc_task is hit deterministically once xfrm_iptfs is unloaded.\nPR:L - xfrm_user_rcv_msg() gates on netlink_net_capable(skb, CAP_NET_ADMIN), which is evaluated against the net namespace\u0027s user_ns, so any unprivileged local user obtains it with `unshare -Urn`; the IPTFS module is auto-loaded on demand by xfrm_get_mode_cbs().\nUI:N - The attacker performs the entire sequence with netlink messages from its own process; no victim action, mount, or file open is needed to arm or trigger the dead state\u0027s deferred GC.\nS:U - The stale callback dereference occurs in kernel context within the same security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - xfrm_state_gc_task loads x-\u003emode_cbs-\u003edestroy_state from module memory that was freed by module unload and can be reoccupied by attacker-influenced allocations, giving a stale-pointer read/indirect-call primitive that can be leveraged to disclose arbitrary kernel memory.\nI:H - Calling a function pointer read out of freed module text/rodata is a control-flow hijack primitive; combined with the missing module reference that lets the memory be recycled, this permits arbitrary kernel-state modification rather than a benign fault.\nA:H - The commit\u0027s reproducer shows the direct outcome is \"BUG: unable to handle page fault\" in the events workqueue running xfrm_state_gc_task, escalating to \"Kernel panic - not syncing: Fatal exception\" \u2014 a full system crash."
            }
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        "dateUpdated": "2026-08-17T05:05:09.173Z",
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        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/2538bd3cd1ff5af655908469544ac7b7ae259386"
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    "datePublished": "2026-08-10T12:04:35.425Z",
    "dateReserved": "2026-07-30T09:28:09.391Z",
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-31T11:27:31+00:00",
      "cve": "CVE-2026-68415",
      "id": "CVE-2026-68415",
      "initial_release_date": "2026-08-10T00:00:00+00:00",
      "product_status:known_not_affected": "277",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: xfrm: clear mode callbacks after failed mode setup",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-68415.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-11T23:46:04Z",
      "cve": "CVE-2026-68415",
      "id": "CVE-2026-68415",
      "initial_release_date": "2026-08-11T23:46:04Z",
      "product_status:known_not_affected": "296",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-68415",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-68415.json",
      "version": "2"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.