CVE-2026-80819
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: RFCOMM: take rfcomm_mutex for the deferred setup accept
rfcomm_sock_recvmsg() completes a deferred setup by calling rfcomm_dlc_accept() without holding any RFCOMM lock:
and rfcomm_dlc_accept() dereferences the session on its first line:
Every other path that touches d->session runs under rfcomm_mutex: rfcomm_dlc_open(), rfcomm_dlc_close(), rfcomm_dlc_exists(), rfcomm_dlc_send_rpn(), and the RFCOMM thread through rfcomm_process_sessions(). rfcomm_connect_ind() is even documented as "called under rfcomm_lock()". This call site is the only one that skips it.
Leer descripción completaMostrar menos
The RFCOMM_DEFER_SETUP bit looks like it serialises the accept against teardown, since __rfcomm_dlc_close() returns early when it wins the test_and_clear. But rfcomm_recv_disc() forces the state first:
and the early return only covers BT_CONNECT, BT_CONFIG, BT_OPEN and BT_CONNECT2. With the state already BT_CLOSED that switch does not match, the bit is never consulted, and __rfcomm_dlc_close() falls through to rfcomm_dlc_unlink(), which sets d->session = NULL.
So a remote DISC on a deferred dlc clears the session while leaving RFCOMM_DEFER_SETUP set. The next recvmsg() then passes the test_and_clear and dereferences a NULL session. No timing window is needed: once the DISC has been processed, the dereference is unconditional.
Give rfcomm_dlc_accept() the same shape as rfcomm_dlc_open() and rfcomm_dlc_close(): an exported wrapper that takes rfcomm_mutex and re-checks the session, around a __rfcomm_dlc_accept() that the two in-core callers, which already hold the mutex, keep using.
Reproduced on a KASAN + PROVE_LOCKING kernel with a BR/EDR peer emulated over /dev/vhci: the peer brings up an ACL link, opens L2CAP on the RFCOMM PSM, starts a session, opens a dlc on a channel bound with BT_DEFER_SETUP, and sends DISC after the socket is accepted. recv() on the accepted socket then hits:
0x10 is the offset of sock in struct rfcomm_session. With this patch the same run completes with recv() returning 0 and no report, and lockdep stays quiet, confirming rfcomm_mutex is still taken before lock_sock on this path as it is on the thread side.
Detalles técnicos trazas, registros y código del informe original
if (test_and_clear_bit(RFCOMM_DEFER_SETUP, &d->flags)) {
rfcomm_dlc_accept(d);
return 0;
}
struct sock *sk = d->session->sock->sk;
d->state = BT_CLOSED;
__rfcomm_dlc_close(d, err);
Oops: general protection fault
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
RIP: 0010:rfcomm_dlc_accept+0x54/0x350
Call Trace:
rfcomm_sock_recvmsg+0x1cd/0x230
sock_recvmsg+0x166/0x1c0
__sys_recvfrom+0x20d/0x300CVSS
NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.19%
- Percentil entre todas las CVEs puntuadas: 8
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
- https://git.kernel.org/stable/c/355bfd57ca4ca881c6eb03ca813b440a094b1f44
- https://git.kernel.org/stable/c/362726c9c6e56eea4262109183e49868c39ccd3a
- https://git.kernel.org/stable/c/43a556b2fd43f2df6dded59c2e26560a27874c24
- https://git.kernel.org/stable/c/56f0aa75c7640e46397ef73bea251fcbef9150c0
- https://git.kernel.org/stable/c/825b95561d7b7c393df9e7bc295451aaeadc3d18
- https://git.kernel.org/stable/c/b405c2f96ae2e37375105881890f7738833b1d62
- https://git.kernel.org/stable/c/d4b1a13b1eff2e80925c7368ffdeaaa50cba93df
- https://git.kernel.org/stable/c/d8d686dd5662a7c4745e4515f1237a9f3b7df181
- https://git.kernel.org/stable/c/eb71d5a1ea8ff2683e394b48ae3cd676037ab4c2
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-80819",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "bb23c0ab824653be4aa7dfca15b07b3059717004",
"lessThan": "d8d686dd5662a7c4745e4515f1237a9f3b7df181",
"versionType": "git"
},
{
"status": "affected",
"version": "bb23c0ab824653be4aa7dfca15b07b3059717004",
"lessThan": "eb71d5a1ea8ff2683e394b48ae3cd676037ab4c2",
"versionType": "git"
},
{
"status": "affected",
"version": "bb23c0ab824653be4aa7dfca15b07b3059717004",
"lessThan": "56f0aa75c7640e46397ef73bea251fcbef9150c0",
"versionType": "git"
},
{
"status": "affected",
"version": "bb23c0ab824653be4aa7dfca15b07b3059717004",
"lessThan": "362726c9c6e56eea4262109183e49868c39ccd3a",
"versionType": "git"
},
{
"status": "affected",
"version": "bb23c0ab824653be4aa7dfca15b07b3059717004",
"lessThan": "825b95561d7b7c393df9e7bc295451aaeadc3d18",
"versionType": "git"
},
{
"status": "affected",
"version": "bb23c0ab824653be4aa7dfca15b07b3059717004",
"lessThan": "d4b1a13b1eff2e80925c7368ffdeaaa50cba93df",
"versionType": "git"
},
{
"status": "affected",
"version": "bb23c0ab824653be4aa7dfca15b07b3059717004",
"lessThan": "355bfd57ca4ca881c6eb03ca813b440a094b1f44",
"versionType": "git"
},
{
"status": "affected",
"version": "bb23c0ab824653be4aa7dfca15b07b3059717004",
"lessThan": "b405c2f96ae2e37375105881890f7738833b1d62",
"versionType": "git"
},
{
"status": "affected",
"version": "bb23c0ab824653be4aa7dfca15b07b3059717004",
"lessThan": "43a556b2fd43f2df6dded59c2e26560a27874c24",
"versionType": "git"
}
],
"programFiles": [
"net/bluetooth/rfcomm/core.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "2.6.30"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "2.6.30",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.267",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.218",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.185",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.154",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.106",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.47",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.1.11",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2.1",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3-rc1",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/bluetooth/rfcomm/core.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-09-04T16:18:09.583",
"references": [
{
"url": "https://git.kernel.org/stable/c/355bfd57ca4ca881c6eb03ca813b440a094b1f44",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/362726c9c6e56eea4262109183e49868c39ccd3a",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/43a556b2fd43f2df6dded59c2e26560a27874c24",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/56f0aa75c7640e46397ef73bea251fcbef9150c0",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/825b95561d7b7c393df9e7bc295451aaeadc3d18",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/b405c2f96ae2e37375105881890f7738833b1d62",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/d4b1a13b1eff2e80925c7368ffdeaaa50cba93df",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/d8d686dd5662a7c4745e4515f1237a9f3b7df181",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/eb71d5a1ea8ff2683e394b48ae3cd676037ab4c2",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: RFCOMM: take rfcomm_mutex for the deferred setup accept\n\nrfcomm_sock_recvmsg() completes a deferred setup by calling\nrfcomm_dlc_accept() without holding any RFCOMM lock:\n\n\tif (test_and_clear_bit(RFCOMM_DEFER_SETUP, &d->flags)) {\n\t\trfcomm_dlc_accept(d);\n\t\treturn 0;\n\t}\n\nand rfcomm_dlc_accept() dereferences the session on its first line:\n\n\tstruct sock *sk = d->session->sock->sk;\n\nEvery other path that touches d->session runs under rfcomm_mutex:\nrfcomm_dlc_open(), rfcomm_dlc_close(), rfcomm_dlc_exists(),\nrfcomm_dlc_send_rpn(), and the RFCOMM thread through\nrfcomm_process_sessions(). rfcomm_connect_ind() is even documented as\n\"called under rfcomm_lock()\". This call site is the only one that skips\nit.\n\nThe RFCOMM_DEFER_SETUP bit looks like it serialises the accept against\nteardown, since __rfcomm_dlc_close() returns early when it wins the\ntest_and_clear. But rfcomm_recv_disc() forces the state first:\n\n\td->state = BT_CLOSED;\n\t__rfcomm_dlc_close(d, err);\n\nand the early return only covers BT_CONNECT, BT_CONFIG, BT_OPEN and\nBT_CONNECT2. With the state already BT_CLOSED that switch does not\nmatch, the bit is never consulted, and __rfcomm_dlc_close() falls\nthrough to rfcomm_dlc_unlink(), which sets d->session = NULL.\n\nSo a remote DISC on a deferred dlc clears the session while leaving\nRFCOMM_DEFER_SETUP set. The next recvmsg() then passes the\ntest_and_clear and dereferences a NULL session. No timing window is\nneeded: once the DISC has been processed, the dereference is\nunconditional.\n\nGive rfcomm_dlc_accept() the same shape as rfcomm_dlc_open() and\nrfcomm_dlc_close(): an exported wrapper that takes rfcomm_mutex and\nre-checks the session, around a __rfcomm_dlc_accept() that the two\nin-core callers, which already hold the mutex, keep using.\n\nReproduced on a KASAN + PROVE_LOCKING kernel with a BR/EDR peer emulated\nover /dev/vhci: the peer brings up an ACL link, opens L2CAP on the\nRFCOMM PSM, starts a session, opens a dlc on a channel bound with\nBT_DEFER_SETUP, and sends DISC after the socket is accepted. recv() on\nthe accepted socket then hits:\n\n Oops: general protection fault\n KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]\n RIP: 0010:rfcomm_dlc_accept+0x54/0x350\n Call Trace:\n rfcomm_sock_recvmsg+0x1cd/0x230\n sock_recvmsg+0x166/0x1c0\n __sys_recvfrom+0x20d/0x300\n\n0x10 is the offset of sock in struct rfcomm_session. With this patch the\nsame run completes with recv() returning 0 and no report, and lockdep\nstays quiet, confirming rfcomm_mutex is still taken before lock_sock on\nthis path as it is on the thread side."
}
],
"lastModified": "2026-09-04T16:18:09.583",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}