Vulnerability-Lookup

GHSA-6CRF-588F-8R2F

Vulnerability from github – Published: 2026-09-17 18:32 – Updated: 2026-09-17 18:32

Details

In the Linux kernel, the following vulnerability has been resolved:

bpf: Drop scalar id on sign-extending narrowing stack fills

When a spilled scalar is filled back with a sign-extending narrowing load (BPF_MEMSX), check_stack_read_fixed_off() copies the spilled register including its scalar id, but coerce_reg_to_size_sx() then sign-extends the filled register's value. If the same slot is also filled with a plain zero-extending load (BPF_MEM), both destination registers share the id yet hold different values. A later 'if == const' then refines the sign-extended register through sync_linked_regs() to a value it does not have at runtime (e.g. the verifier believes 0x80000000 while the register is 0xffffffff80000000), which can be turned into an out-of-bounds access.

Drop the shared scalar id at the sign-extension site in check_mem_access() when sign extension actually changes the value, mirroring the BPF_MOVSX handling in check_alu_op() (no_sext = reg_umax < 2^(size*8-1)).

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{
  "affected": [],
  "aliases": [
    "CVE-2026-93127"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-17T17:18:07Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Drop scalar id on sign-extending narrowing stack fills\n\nWhen a spilled scalar is filled back with a sign-extending narrowing load\n(BPF_MEMSX), check_stack_read_fixed_off() copies the spilled register\nincluding its scalar id, but coerce_reg_to_size_sx() then sign-extends the\nfilled register\u0027s value. If the same slot is also filled with a plain\nzero-extending load (BPF_MEM), both destination registers share the id yet\nhold different values. A later \u0027if \u003czext-reg\u003e == const\u0027 then refines the\nsign-extended register through sync_linked_regs() to a value it does not\nhave at runtime (e.g. the verifier believes 0x80000000 while the register\nis 0xffffffff80000000), which can be turned into an out-of-bounds access.\n\nDrop the shared scalar id at the sign-extension site in check_mem_access()\nwhen sign extension actually changes the value, mirroring the BPF_MOVSX\nhandling in check_alu_op() (no_sext = reg_umax \u003c 2^(size*8-1)).",
  "id": "GHSA-6crf-588f-8r2f",
  "modified": "2026-09-17T18:32:11Z",
  "published": "2026-09-17T18:32:11Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-93127"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2cb5f4ca695ebe552647e5ba4aad6934d6a43bae"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f3614622dc41f3dd99bb4f691da253814e4e6cae"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-93127 (GCVE-0-2026-93127)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:11 – Updated: 2026-09-17 16:11

Title

bpf: Drop scalar id on sign-extending narrowing stack fills

Summary

In the Linux kernel, the following vulnerability has been resolved: bpf: Drop scalar id on sign-extending narrowing stack fills When a spilled scalar is filled back with a sign-extending narrowing load (BPF_MEMSX), check_stack_read_fixed_off() copies the spilled register including its scalar id, but coerce_reg_to_size_sx() then sign-extends the filled register's value. If the same slot is also filled with a plain zero-extending load (BPF_MEM), both destination registers share the id yet hold different values. A later 'if <zext-reg> == const' then refines the sign-extended register through sync_linked_regs() to a value it does not have at runtime (e.g. the verifier believes 0x80000000 while the register is 0xffffffff80000000), which can be turned into an out-of-bounds access. Drop the shared scalar id at the sign-extension site in check_mem_access() when sign extension actually changes the value, mirroring the BPF_MOVSX handling in check_alu_op() (no_sext = reg_umax < 2^(size*8-1)).

Severity

No CVSS data available.

Assigner

Linux mitre root

References

2 references

URL	Tags
https://git.kernel.org/stable/c/f3614622dc41f3dd9…
https://git.kernel.org/stable/c/2cb5f4ca695ebe552…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 3cd5c890652ba1f0682adc291b5446245259b692 , < f3614622dc41f3dd99bb4f691da253814e4e6cae (git) Affected: 3cd5c890652ba1f0682adc291b5446245259b692 , < 2cb5f4ca695ebe552647e5ba4aad6934d6a43bae (git)
Linux	Linux	Affected: 7.0 Unaffected: 0 , < 7.0 (semver) Unaffected: 7.2.6 , ≤ 7.2.* (semver) Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/verifier.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
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              "status": "affected",
              "version": "3cd5c890652ba1f0682adc291b5446245259b692",
              "versionType": "git"
            },
            {
              "lessThan": "2cb5f4ca695ebe552647e5ba4aad6934d6a43bae",
              "status": "affected",
              "version": "3cd5c890652ba1f0682adc291b5446245259b692",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/verifier.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
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              "version": "7.0"
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              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
            {
              "cpeMatch": [
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                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc1",
                  "versionStartIncluding": "7.0",
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                }
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              "operator": "OR"
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        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Drop scalar id on sign-extending narrowing stack fills\n\nWhen a spilled scalar is filled back with a sign-extending narrowing load\n(BPF_MEMSX), check_stack_read_fixed_off() copies the spilled register\nincluding its scalar id, but coerce_reg_to_size_sx() then sign-extends the\nfilled register\u0027s value. If the same slot is also filled with a plain\nzero-extending load (BPF_MEM), both destination registers share the id yet\nhold different values. A later \u0027if \u003czext-reg\u003e == const\u0027 then refines the\nsign-extended register through sync_linked_regs() to a value it does not\nhave at runtime (e.g. the verifier believes 0x80000000 while the register\nis 0xffffffff80000000), which can be turned into an out-of-bounds access.\n\nDrop the shared scalar id at the sign-extension site in check_mem_access()\nwhen sign extension actually changes the value, mirroring the BPF_MOVSX\nhandling in check_alu_op() (no_sext = reg_umax \u003c 2^(size*8-1))."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-17T16:11:31.253Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/2cb5f4ca695ebe552647e5ba4aad6934d6a43bae"
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      "title": "bpf: Drop scalar id on sign-extending narrowing stack fills",
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  "cveMetadata": {
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    "datePublished": "2026-09-17T16:11:31.253Z",
    "dateReserved": "2026-09-17T16:02:15.087Z",
    "dateUpdated": "2026-09-17T16:11:31.253Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
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}

Sightings

Author	Source	Type	Date	Other

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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