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GHSA-8H97-6438-987H

Vulnerability from github – Published: 2026-04-22 15:31 – Updated: 2026-04-27 15:30

Details

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

Bluetooth: L2CAP: Fix stack-out-of-bounds read in l2cap_ecred_conn_req

Syzbot reported a KASAN stack-out-of-bounds read in l2cap_build_cmd() that is triggered by a malformed Enhanced Credit Based Connection Request.

The vulnerability stems from l2cap_ecred_conn_req(). The function allocates a local stack buffer (pdu) designed to hold a maximum of 5 Source Channel IDs (SCIDs), totaling 18 bytes. When an attacker sends a request with more than 5 SCIDs, the function calculates rsp_len based on this unvalidated cmd_len before checking if the number of SCIDs exceeds L2CAP_ECRED_MAX_CID.

If the SCID count is too high, the function correctly jumps to the response label to reject the packet, but rsp_len retains the attacker's oversized value. Consequently, l2cap_send_cmd() is instructed to read past the end of the 18-byte pdu buffer, triggering a KASAN panic.

Fix this by moving the assignment of rsp_len to after the num_scid boundary check. If the packet is rejected, rsp_len will safely remain 0, and the error response will only read the 8-byte base header from the stack.

Severity

8.1 (High)


                  
                    CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-31513"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-125"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-04-22T14:16:50Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: Fix stack-out-of-bounds read in l2cap_ecred_conn_req\n\nSyzbot reported a KASAN stack-out-of-bounds read in l2cap_build_cmd()\nthat is triggered by a malformed Enhanced Credit Based Connection Request.\n\nThe vulnerability stems from l2cap_ecred_conn_req(). The function allocates\na local stack buffer (`pdu`) designed to hold a maximum of 5 Source Channel\nIDs (SCIDs), totaling 18 bytes. When an attacker sends a request with more\nthan 5 SCIDs, the function calculates `rsp_len` based on this unvalidated\n`cmd_len` before checking if the number of SCIDs exceeds\nL2CAP_ECRED_MAX_CID.\n\nIf the SCID count is too high, the function correctly jumps to the\n`response` label to reject the packet, but `rsp_len` retains the\nattacker\u0027s oversized value. Consequently, l2cap_send_cmd() is instructed\nto read past the end of the 18-byte `pdu` buffer, triggering a\nKASAN panic.\n\nFix this by moving the assignment of `rsp_len` to after the `num_scid`\nboundary check. If the packet is rejected, `rsp_len` will safely\nremain 0, and the error response will only read the 8-byte base header\nfrom the stack.",
  "id": "GHSA-8h97-6438-987h",
  "modified": "2026-04-27T15:30:39Z",
  "published": "2026-04-22T15:31:43Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31513"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5b35f8211a913cfe7ab9d54fa36a272d2059a588"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9d87cb22195b2c67405f5485d525190747ad5493"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a3d9c50d69785ae02e153f000da1b5fd6dbfdf1b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c8e1a27edb8b4e5afb56b384acd7b6c2dec1b7cc"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-31513 (GCVE-0-2026-31513)

Vulnerability from cvelistv5 – Published: 2026-04-22 13:54 – Updated: 2026-08-05 12:23

Title

Bluetooth: L2CAP: Fix stack-out-of-bounds read in l2cap_ecred_conn_req

Summary

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: Fix stack-out-of-bounds read in l2cap_ecred_conn_req Syzbot reported a KASAN stack-out-of-bounds read in l2cap_build_cmd() that is triggered by a malformed Enhanced Credit Based Connection Request. The vulnerability stems from l2cap_ecred_conn_req(). The function allocates a local stack buffer (`pdu`) designed to hold a maximum of 5 Source Channel IDs (SCIDs), totaling 18 bytes. When an attacker sends a request with more than 5 SCIDs, the function calculates `rsp_len` based on this unvalidated `cmd_len` before checking if the number of SCIDs exceeds L2CAP_ECRED_MAX_CID. If the SCID count is too high, the function correctly jumps to the `response` label to reject the packet, but `rsp_len` retains the attacker's oversized value. Consequently, l2cap_send_cmd() is instructed to read past the end of the 18-byte `pdu` buffer, triggering a KASAN panic. Fix this by moving the assignment of `rsp_len` to after the `num_scid` boundary check. If the packet is rejected, `rsp_len` will safely remain 0, and the error response will only read the 8-byte base header from the stack.

Severity

8.1 (High)


                        
                          CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Assigner

Linux mitre root

References

4 references

URL	Tags
https://git.kernel.org/stable/c/c8e1a27edb8b4e5af…
https://git.kernel.org/stable/c/5b35f8211a913cfe7…
https://git.kernel.org/stable/c/a3d9c50d69785ae02…
https://git.kernel.org/stable/c/9d87cb22195b2c674…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 935f324e4b2461df2cf7f02b4195082b4304c708 , < c8e1a27edb8b4e5afb56b384acd7b6c2dec1b7cc (git) Affected: e981a9392800ce2c5bca196a6ab2c55e9370efaa , < 5b35f8211a913cfe7ab9d54fa36a272d2059a588 (git) Affected: f3fdf2e7276a3edc5df55454275da20eac186970 , < a3d9c50d69785ae02e153f000da1b5fd6dbfdf1b (git) Affected: c28d2bff70444a85b3b86aaf241ece9408c7858c , < 9d87cb22195b2c67405f5485d525190747ad5493 (git)
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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JSON

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      "affected": [
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          "defaultStatus": "unaffected",
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          "programFiles": [
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          "vendor": "Linux",
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              "versionType": "git"
            }
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        },
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          "defaultStatus": "unaffected",
          "product": "Linux",
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          ],
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          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "6.12.80",
              "status": "affected",
              "version": "6.12.75",
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      "cpeApplicability": [
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          "nodes": [
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              "cpeMatch": [
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                }
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            }
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      "descriptions": [
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: Fix stack-out-of-bounds read in l2cap_ecred_conn_req\n\nSyzbot reported a KASAN stack-out-of-bounds read in l2cap_build_cmd()\nthat is triggered by a malformed Enhanced Credit Based Connection Request.\n\nThe vulnerability stems from l2cap_ecred_conn_req(). The function allocates\na local stack buffer (`pdu`) designed to hold a maximum of 5 Source Channel\nIDs (SCIDs), totaling 18 bytes. When an attacker sends a request with more\nthan 5 SCIDs, the function calculates `rsp_len` based on this unvalidated\n`cmd_len` before checking if the number of SCIDs exceeds\nL2CAP_ECRED_MAX_CID.\n\nIf the SCID count is too high, the function correctly jumps to the\n`response` label to reject the packet, but `rsp_len` retains the\nattacker\u0027s oversized value. Consequently, l2cap_send_cmd() is instructed\nto read past the end of the 18-byte `pdu` buffer, triggering a\nKASAN panic.\n\nFix this by moving the assignment of `rsp_len` to after the `num_scid`\nboundary check. If the packet is rejected, `rsp_len` will safely\nremain 0, and the error response will only read the 8-byte base header\nfrom the stack."
        }
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          },
          "scenarios": [
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              "lang": "en",
              "value": "AV:A - The vulnerable code is reached by a Bluetooth LE L2CAP signaling packet from a nearby Bluetooth peer, so exploitation requires adjacent radio proximity rather than internet routing or local code execution.\nAC:L - The attacker only needs to send a malformed Enhanced Credit Based Connection Request with more than 5 SCIDs; the bad length is used deterministically before the bounds check.\nPR:N - The vulnerable path is reached before PSM lookup and before `smp_sufficient_security()`, so no pairing, authentication, service authorization, or local privilege is required.\nUI:N - Once the target is reachable over Bluetooth LE, the malformed signaling request is processed by the kernel without requiring a victim user action.\nS:U - The impact is within the kernel Bluetooth stack on the same host security authority; this is not a cross-VM, IOMMU, or sandbox boundary escape by itself.\nC:H - The oversized response length causes `l2cap_send_cmd()` to copy beyond an 18-byte stack buffer into an outbound L2CAP response, exposing attacker-sized kernel stack contents rather than a strictly bounded few bytes.\nI:N - The bug is an out-of-bounds read used to build a response packet; it does not provide an out-of-bounds write or direct modification of kernel data.\nA:H - The same malformed packet triggers a demonstrated KASAN stack-out-of-bounds panic, and a sufficiently large kernel stack read can reasonably crash the kernel even outside KASAN builds."
            }
          ]
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      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:23:12.375Z",
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          "url": "https://git.kernel.org/stable/c/5b35f8211a913cfe7ab9d54fa36a272d2059a588"
        },
        {
          "url": "https://git.kernel.org/stable/c/a3d9c50d69785ae02e153f000da1b5fd6dbfdf1b"
        },
        {
          "url": "https://git.kernel.org/stable/c/9d87cb22195b2c67405f5485d525190747ad5493"
        }
      ],
      "title": "Bluetooth: L2CAP: Fix stack-out-of-bounds read in l2cap_ecred_conn_req",
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    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-31513",
    "datePublished": "2026-04-22T13:54:30.835Z",
    "dateReserved": "2026-03-09T15:48:24.107Z",
    "dateUpdated": "2026-08-05T12:23:12.375Z",
    "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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