{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2026-64127", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-64127", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-07-19T15:40:23.960Z", "updatedAt": "2026-07-19T15:40:23.960Z", "importedAt": "2026-10-24T01:58:25.636Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "Bluetooth: L2CAP: ecred_reconfigure: send packed pdu, not stack pointer", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: ecred_reconfigure: send packed pdu, not stack pointer\n\nCommit 1c08108f3014 (\"Bluetooth: L2CAP: Avoid -Wflex-array-member-not-at-end\nwarnings\") converted the on-stack request PDU in l2cap_ecred_reconfigure()\nfrom an explicit packed struct to DEFINE_RAW_FLEX(), but did not adjust the\nsize and source-pointer arguments to l2cap_send_cmd():\n\n - struct {\n - struct l2cap_ecred_reconf_req req;\n - __le16 scid;\n - } pdu;\n + DEFINE_RAW_FLEX(struct l2cap_ecred_reconf_req, pdu, scid, 1);\n ...\n l2cap_send_cmd(conn, chan->ident, L2CAP_ECRED_RECONF_REQ,\n sizeof(pdu), &pdu);\n\nAfter the conversion, DEFINE_RAW_FLEX() expands to declare an anonymous\nunion pdu_u plus a local pointer \"pdu\" pointing at it. Therefore:\n\n - sizeof(pdu) is now sizeof(struct l2cap_ecred_reconf_req *) = 8 on\n 64-bit (4 on 32-bit), not the 6 bytes of (mtu, mps, scid[1]).\n - &pdu is the address of the local pointer's stack storage, not the\n address of the request payload.\n\nl2cap_send_cmd() forwards (data, count) to l2cap_build_cmd(), which calls\nskb_put_data(skb, data, count). The L2CAP_ECRED_RECONFIGURE_REQ packet\nbody therefore contains 8 bytes copied from the kernel stack starting at\n&pdu -- the 8 bytes overlap the pdu pointer's value, leaking a kernel\nstack address to the paired Bluetooth peer. The intended (mtu, mps, scid)\nfields are not transmitted at all, so the peer rejects the request as\nmalformed and the L2CAP_ECRED_RECONFIGURE feature itself has been broken\nfor the local-side initiator since the introducing commit landed.\n\nThe sibling site l2cap_ecred_conn_req() in the same commit was converted\ncorrectly (sizeof(*pdu) + len, pdu); only this site was missed.\n\nRestore the original semantics: pass the full flex-struct size via\nstruct_size(pdu, scid, 1) and the pdu pointer (the struct address) as\nthe source.\n\nValidated on a stock 7.0-based host kernel via the real call path:\nsetsockopt(SOL_BLUETOOTH, BT_RCVMTU, ...) on a BT_CONNECTED\nL2CAP_MODE_EXT_FLOWCTL socket emits an L2CAP_ECRED_RECONFIGURE_REQ\nwhose body is 8 bytes (the on-stack pdu local's value) rather than\nthe expected 6. Three captures from fresh socket / fresh hciemu peer\non the same host -- low bytes vary per call, high 0xffff confirms a\nkernel virtual address (KASLR-randomised stack slot, not a fixed\nstring):\n\n RECONF_REQ body (ident=0x02 len=8): 42 fb 54 af 0e ca ff ff\n RECONF_REQ body (ident=0x02 len=8): 52 3d 2e af 0e ca ff ff\n RECONF_REQ body (ident=0x02 len=8): b2 fc 5b af 0e ca ff ff\n\nAfter this patch the body is 6 bytes carrying the expected\nlittle-endian (mtu, mps, scid).", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "1c08108f3014881ad5f4c35a2abaf9c65475035d", "status": "affected", "versionType": "git", "lessThan": "ed5fcd2a26f0c16fc289c8cd6b03328a0582a687" }, { "version": "1c08108f3014881ad5f4c35a2abaf9c65475035d", "status": "affected", "versionType": "git", "lessThan": "051922ab709c0a6917eae765c22481dfc68379e5" }, { "version": "1c08108f3014881ad5f4c35a2abaf9c65475035d", "status": "affected", "versionType": "git", "lessThan": "356c9d1a1cbacd2a1640fff3c050e1c3472e924f" }, { "version": "1c08108f3014881ad5f4c35a2abaf9c65475035d", "status": "affected", "versionType": "git", "lessThan": "3374ef8cf99368a40f7efd51a2a375a4c5dc6f0d" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "6.10", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "6.10" }, { "version": "6.12.92", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.18.34", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.18.*" }, { "version": "7.0.11", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.0.*" }, { "version": "7.1", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }