DEBIAN-CVE-2026-64127
- Source
- https://security-tracker.debian.org/tracker/CVE-2026-64127
- Import Source
- https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-64127.json
- JSON Data
- https://api.test.osv.dev/v1/vulns/DEBIAN-CVE-2026-64127
- Upstream
- Published
- 2026-07-19T16:17:54Z
- Modified
- 2026-08-27T23:06:18Z
- Severity
-
- 5.5 (Medium) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
- Summary
- [none]
- Details
-
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: ecred_reconfigure: send packed pdu, not stack pointer Commit 1c08108f3014 ("Bluetooth: L2CAP: Avoid -Wflex-array-member-not-at-end warnings") converted the on-stack request PDU in l2cap_ecred_reconfigure() from an explicit packed struct to DEFINE_RAW_FLEX(), but did not adjust the size and source-pointer arguments to l2cap_send_cmd(): - struct { - struct l2cap_ecred_reconf_req req; - __le16 scid; - } pdu; + DEFINE_RAW_FLEX(struct l2cap_ecred_reconf_req, pdu, scid, 1); ... l2cap_send_cmd(conn, chan->ident, L2CAP_ECRED_RECONF_REQ, sizeof(pdu), &pdu); After the conversion, DEFINE_RAW_FLEX() expands to declare an anonymous union pdu_u plus a local pointer "pdu" pointing at it. Therefore: - sizeof(pdu) is now sizeof(struct l2cap_ecred_reconf_req *) = 8 on 64-bit (4 on 32-bit), not the 6 bytes of (mtu, mps, scid[1]). - &pdu is the address of the local pointer's stack storage, not the address of the request payload. l2cap_send_cmd() forwards (data, count) to l2cap_build_cmd(), which calls skb_put_data(skb, data, count). The L2CAP_ECRED_RECONFIGURE_REQ packet body therefore contains 8 bytes copied from the kernel stack starting at &pdu -- the 8 bytes overlap the pdu pointer's value, leaking a kernel stack address to the paired Bluetooth peer. The intended (mtu, mps, scid) fields are not transmitted at all, so the peer rejects the request as malformed and the L2CAP_ECRED_RECONFIGURE feature itself has been broken for the local-side initiator since the introducing commit landed. The sibling site l2cap_ecred_conn_req() in the same commit was converted correctly (sizeof(*pdu) + len, pdu); only this site was missed. Restore the original semantics: pass the full flex-struct size via struct_size(pdu, scid, 1) and the pdu pointer (the struct address) as the source. Validated on a stock 7.0-based host kernel via the real call path: setsockopt(SOL_BLUETOOTH, BT_RCVMTU, ...) on a BT_CONNECTED L2CAP_MODE_EXT_FLOWCTL socket emits an L2CAP_ECRED_RECONFIGURE_REQ whose body is 8 bytes (the on-stack pdu local's value) rather than the expected 6. Three captures from fresh socket / fresh hciemu peer on the same host -- low bytes vary per call, high 0xffff confirms a kernel virtual address (KASLR-randomised stack slot, not a fixed string): RECONF_REQ body (ident=0x02 len=8): 42 fb 54 af 0e ca ff ff RECONF_REQ body (ident=0x02 len=8): 52 3d 2e af 0e ca ff ff RECONF_REQ body (ident=0x02 len=8): b2 fc 5b af 0e ca ff ff After this patch the body is 6 bytes carrying the expected little-endian (mtu, mps, scid).
- References
Affected packages
Debian:13 / linux
Package
- Name
- linux
- Purl
- pkg:deb/debian/linux?arch=source&distro=trixie
Affected ranges
- Type
- ECOSYSTEM
- Events
-
Introduced0 Unknown introduced version / All previous versions are affectedFixed6.12.94-1
Affected versions
6.*
Debian:14 / linux
Package
- Name
- linux
- Purl
- pkg:deb/debian/linux?arch=source&distro=forky
Affected ranges
- Type
- ECOSYSTEM
- Events
-
Introduced0 Unknown introduced version / All previous versions are affectedFixed7.0.12-1