CVE-2026-31413 (GCVE-0-2026-31413)

Vulnerability from cvelistv5 – Published: 2026-04-12 05:36 – Updated: 2026-08-05 12:22
VLAI
Title
bpf: Fix unsound scalar forking in maybe_fork_scalars() for BPF_OR
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix unsound scalar forking in maybe_fork_scalars() for BPF_OR maybe_fork_scalars() is called for both BPF_AND and BPF_OR when the source operand is a constant. When dst has signed range [-1, 0], it forks the verifier state: the pushed path gets dst = 0, the current path gets dst = -1. For BPF_AND this is correct: 0 & K == 0. For BPF_OR this is wrong: 0 | K == K, not 0. The pushed path therefore tracks dst as 0 when the runtime value is K, producing an exploitable verifier/runtime divergence that allows out-of-bounds map access. Fix this by passing env->insn_idx (instead of env->insn_idx + 1) to push_stack(), so the pushed path re-executes the ALU instruction with dst = 0 and naturally computes the correct result for any opcode.
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: dea9989a3f3961faede93752cd81eb5a9514d911 , < 342aa1ee995ef5bbf876096dc3a5e51218d76fa4 (git)
Affected: 4c122e8ae14950cf6b59d208fc5160f7c601e746 , < 58bd87d0e69204dbd739e4387a1edb0c4b1644e7 (git)
Affected: e52567173ba86dbffb990595fbe60e2e83899372 , < d13281ae7ea8902b21d99d10a2c8caf0bdec0455 (git)
Affected: bffacdb80b93b7b5e96b26fad64cc490a6c7d6c7 , < c845894ebd6fb43226b3118d6b017942550910c5 (git)
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Linux Linux Affected: 6.12.75 , < 6.12.80 (semver)
Affected: 6.18.16 , < 6.18.21 (semver)
Affected: 6.19.6 , < 6.19.11 (semver)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/verifier.c"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix unsound scalar forking in maybe_fork_scalars() for BPF_OR\n\nmaybe_fork_scalars() is called for both BPF_AND and BPF_OR when the\nsource operand is a constant.  When dst has signed range [-1, 0], it\nforks the verifier state: the pushed path gets dst = 0, the current\npath gets dst = -1.\n\nFor BPF_AND this is correct: 0 \u0026 K == 0.\nFor BPF_OR this is wrong:    0 | K == K, not 0.\n\nThe pushed path therefore tracks dst as 0 when the runtime value is K,\nproducing an exploitable verifier/runtime divergence that allows\nout-of-bounds map access.\n\nFix this by passing env-\u003einsn_idx (instead of env-\u003einsn_idx + 1) to\npush_stack(), so the pushed path re-executes the ALU instruction with\ndst = 0 and naturally computes the correct result for any opcode."
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              "value": "AV:L - The vulnerable verifier path is reached through the local bpf() syscall during BPF_PROG_LOAD, not through a remote protocol. A plausible path is an attacker-supplied socket-filter BPF program using attacker-created maps.\nAC:L - The attacker controls the BPF bytecode, map layout, and scalar values needed to trigger the verifier/runtime divergence. There is no race or external condition beyond attacker control.\nPR:L - Exploitation requires a local user able to load BPF programs, which can be a basic unprivileged user where unprivileged BPF is enabled or a delegated BPF capability path exists. It does not inherently require real init-namespace root for the vulnerable verifier logic.\nUI:N - No victim action is required after the attacker loads and runs the crafted BPF program. The trigger is fully under the local attacker\u0027s control.\nS:U - This is a standard kernel privilege-escalation style BPF verifier flaw within the same host kernel security authority. It does not cross a VM, hypervisor, or IOMMU boundary.\nC:H - The verifier/runtime divergence allows out-of-bounds map-value reads, which can expose adjacent kernel heap data and be developed into broader kernel memory disclosure. BPF verifier OOB map-access bugs are commonly exploitable as kernel read primitives.\nI:H - The same incorrect bounds reasoning can be applied to writes through map-value pointers, enabling out-of-bounds kernel heap corruption. That is sufficient for arbitrary kernel memory modification or code execution in a defensible worst case.\nA:H - Out-of-bounds BPF memory access can corrupt kernel memory or fault the kernel, causing an oops, panic, or hang. Even failed exploitation can be repeatedly triggered by the local attacker."
            }
          ]
        }
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        "dateUpdated": "2026-08-05T12:22:19.762Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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    "datePublished": "2026-04-12T05:36:14.632Z",
    "dateReserved": "2026-03-09T15:48:24.087Z",
    "dateUpdated": "2026-08-05T12:22:19.762Z",
    "state": "PUBLISHED"
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    "redhat_vex": {
      "aggregate_severity": "None",
      "current_release_date": "2026-06-28T07:25:13+00:00",
      "cve": "CVE-2026-31413",
      "id": "CVE-2026-31413",
      "initial_release_date": "2026-04-12T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: bpf: Fix unsound scalar forking in maybe_fork_scalars() for BPF_OR",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-31413.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-08-06T01:25:21Z",
      "cve": "CVE-2026-31413",
      "id": "CVE-2026-31413",
      "initial_release_date": "2026-04-12T23:24:41Z",
      "product_status:known_not_affected": "305",
      "product_status:recommended": "27",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-31413",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-31413.json",
      "version": "6"
    }
  }
}



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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.