CVE-2026-68337 (GCVE-0-2026-68337)

Vulnerability from cvelistv5 – Published: 2026-08-10 12:03 – Updated: 2026-09-21 13:13
VLAI
Title
bpf: Reject redirect helpers without a bpf_net_context
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Reject redirect helpers without a bpf_net_context The bpf_redirect*() helpers and skb_do_redirect() obtain the per-task bpf_redirect_info via bpf_net_ctx_get_ri(), which dereferences the current->bpf_net_context unconditionally. That context is established on the paths that run tc BPF such as sch_handle_{ingress,egress}(), *except* for the case where {cls,act}_bpf was attached to a proper qdisc. A program running from there reaches the NULL deref in two ways: * It calls bpf_redirect() directly, which dereferences the context at the top of the helper: tc qdisc add dev eth0 root handle 1: red limit 1MB min 10KB max 20KB \ avpkt 1000 burst 100 qevent early_drop block 10 tc filter add block 10 pref 1 bpf obj redirect.o * It simply returns TC_ACT_REDIRECT without helper call: tcf_qevent_handle() then dispatches to skb_do_redirect(), which dereferences the context Rather than extending bpf_net_context management into the qdisc path, make the redirect helpers refuse to operate when no context exists, and have tcf_qevent_handle() drop a TC_ACT_REDIRECT verdict instead of calling skb_do_redirect(). Previous behaviour was a crash, so nothing regresses by not supporting it.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 3625750f05ecce21a0fce429c1ff85acfffb461b , < 0f2118b757509332bb0e65f90e5233766f14bb88 (git)
Affected: 3625750f05ecce21a0fce429c1ff85acfffb461b , < aafb093adffad91d4d071e8a7e0dcd9b1d91c94a (git)
Affected: 3625750f05ecce21a0fce429c1ff85acfffb461b , < cabfacbd5af09d3ae898ca224c4a1459e9bba15d (git)
Affected: 3625750f05ecce21a0fce429c1ff85acfffb461b , < 3f4920d165b29052255527d8ae7619e7ec132ece (git)
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Linux Linux Affected: 5.9
Unaffected: 0 , < 5.9 (semver)
Unaffected: 6.12.111 , ≤ 6.12.* (semver)
Unaffected: 6.18.53 , ≤ 6.18.* (semver)
Unaffected: 7.1.6 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
            "net/core/filter.c",
            "net/sched/cls_api.c"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject redirect helpers without a bpf_net_context\n\nThe bpf_redirect*() helpers and skb_do_redirect() obtain the per-task\nbpf_redirect_info via bpf_net_ctx_get_ri(), which dereferences the\ncurrent-\u003ebpf_net_context unconditionally. That context is established\non the paths that run tc BPF such as sch_handle_{ingress,egress}(),\n*except* for the case where {cls,act}_bpf was attached to a proper\nqdisc. A program running from there reaches the NULL deref in two ways:\n\n* It calls bpf_redirect() directly, which dereferences the context at\n  the top of the helper:\n\n     tc qdisc add dev eth0 root handle 1: red limit 1MB min 10KB max 20KB \\\n        avpkt 1000 burst 100 qevent early_drop block 10\n     tc filter add block 10 pref 1 bpf obj redirect.o\n\n* It simply returns TC_ACT_REDIRECT without helper call: tcf_qevent_handle()\n  then dispatches to skb_do_redirect(), which dereferences the context\n\nRather than extending bpf_net_context management into the qdisc path,\nmake the redirect helpers refuse to operate when no context exists, and\nhave tcf_qevent_handle() drop a TC_ACT_REDIRECT verdict instead of\ncalling skb_do_redirect(). Previous behaviour was a crash, so nothing\nregresses by not supporting it."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-21T13:13:42.530Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/cabfacbd5af09d3ae898ca224c4a1459e9bba15d"
        },
        {
          "url": "https://git.kernel.org/stable/c/3f4920d165b29052255527d8ae7619e7ec132ece"
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      "title": "bpf: Reject redirect helpers without a bpf_net_context",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-68337",
    "datePublished": "2026-08-10T12:03:13.583Z",
    "dateReserved": "2026-07-30T09:28:09.383Z",
    "dateUpdated": "2026-09-21T13:13:42.530Z",
    "state": "PUBLISHED"
  },
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        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject redirect helpers without a bpf_net_context\n\nThe bpf_redirect*() helpers and skb_do_redirect() obtain the per-task\nbpf_redirect_info via bpf_net_ctx_get_ri(), which dereferences the\ncurrent-\u003ebpf_net_context unconditionally. That context is established\non the paths that run tc BPF such as sch_handle_{ingress,egress}(),\n*except* for the case where {cls,act}_bpf was attached to a proper\nqdisc. A program running from there reaches the NULL deref in two ways:\n\n* It calls bpf_redirect() directly, which dereferences the context at\n  the top of the helper:\n\n     tc qdisc add dev eth0 root handle 1: red limit 1MB min 10KB max 20KB \\\n        avpkt 1000 burst 100 qevent early_drop block 10\n     tc filter add block 10 pref 1 bpf obj redirect.o\n\n* It simply returns TC_ACT_REDIRECT without helper call: tcf_qevent_handle()\n  then dispatches to skb_do_redirect(), which dereferences the context\n\nRather than extending bpf_net_context management into the qdisc path,\nmake the redirect helpers refuse to operate when no context exists, and\nhave tcf_qevent_handle() drop a TC_ACT_REDIRECT verdict instead of\ncalling skb_do_redirect(). Previous behaviour was a crash, so nothing\nregresses by not supporting it."
          }
        ],
        "id": "CVE-2026-68337",
        "lastModified": "2026-09-21T14:17:16.860",
        "metrics": {},
        "published": "2026-08-10T13:20:24.120",
        "references": [
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        "vulnStatus": "Received"
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      "current_release_date": "2026-08-14T14:19:43+00:00",
      "cve": "CVE-2026-68337",
      "id": "CVE-2026-68337",
      "initial_release_date": "2026-08-10T12:03:13.583000+00:00",
      "product_status:known_affected": "233",
      "product_status:known_not_affected": "42",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: Linux kernel: Denial of Service in BPF redirect helpers",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-68337.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-15T01:36:01Z",
      "cve": "CVE-2026-68337",
      "id": "CVE-2026-68337",
      "initial_release_date": "2026-08-11T23:47:22Z",
      "product_status:known_affected": "253",
      "product_status:known_not_affected": "121",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-68337",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-68337.json",
      "version": "4"
    }
  }
}



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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.


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Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.