CVE-2019-9506 | Blutooth BR/EDR specification does not specify sufficient encryption key length and allows an attacker to influence key length negotiation

The Bluetooth BR/EDR specification up to and including version 5.1 permits sufficiently low encryption key length and does not prevent an attacker from influencing the key length negotiation. This allows practical brute-force attacks (aka "KNOB") that can decrypt traffic and inject arbitrary ciphertext without the victim noticing.

Published: 2019-08-14 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2019-9506 is rated Moderate Risk (60.3/100): CVSS High severity, with medium exploitation likelihood (EPSS 2.69%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2019-9506

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 4.15% 2.69% -1.45%
2 2026-05-26 4.46% 4.15% -0.31%
3 2026-04-29 — 4.46% —

Full EPSS history (71 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2019-9506

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.1 3.1 HIGH
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N Click to expand
Attack vector (AV:A)
Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 5.2 [email protected]
7.6 3.0 HIGH
CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L Click to expand
Attack vector (AV:A)
Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 2.8 4.7 [email protected]
4.8 2.0 MEDIUM
AV:A/AC:L/Au:N/C:P/I:P/A:N Click to expand
Access vector (AV:A)
Requires access to an adjacent network segment.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 6.5 4.9 [email protected]

Weakness enumeration for CVE-2019-9506

OS Trackers for CVE-2019-9506

vendor priority summary link
debian not yet assigned CVE-2019-9506 not yet assigned priority: Debian including 1 source packages (linux), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2019-9506
redhat high — https://access.redhat.com/security/cve/CVE-2019-9506
suse medium CVE-2019-9506 severity moderate: SUSE including 282 source package names (bluez, bluez-cups, …), 642 product×package rows across 99 product lines (HPE Helion OpenStack 8, Image SLES12-SP5-Azure-BYOS, … (99 product lines)): Fixed 593, Known Not Affected 49. https://www.suse.com/security/cve/CVE-2019-9506/
ubuntu medium CVE-2019-9506 medium priority: Ubuntu including 111 source packages (linux, linux-aws, …), 1148 status rows across 13 suites (bionic, disco, eoan, focal, groovy, jammy, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 809, not-affected 181, released 147, ignored 10, needed 1. https://ubuntu.com/security/CVE-2019-9506

Affected software / configurations for CVE-2019-9506

Vendor Product Version Raw CPE
google android — cpe:2.3:o:google:android:-:*:*:*:*:*:*:*
apple iphone_os 12.4 cpe:2.3:o:apple:iphone_os:12.4:*:*:*:*:*:*:*
apple mac_os_x 10.12.6 cpe:2.3:o:apple:mac_os_x:10.12.6:*:*:*:*:*:*:*
apple mac_os_x 10.13.6 cpe:2.3:o:apple:mac_os_x:10.13.6:*:*:*:*:*:*:*
apple mac_os_x 10.14.5 cpe:2.3:o:apple:mac_os_x:10.14.5:*:*:*:*:*:*:*
apple tvos 12.4 cpe:2.3:o:apple:tvos:12.4:*:*:*:*:*:*:*
apple watchos 5.3 cpe:2.3:o:apple:watchos:5.3:*:*:*:*:*:*:*
canonical ubuntu_linux 16.04 cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:*
canonical ubuntu_linux 18.04 cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
canonical ubuntu_linux 19.04 cpe:2.3:o:canonical:ubuntu_linux:19.04:*:*:*:*:*:*:*
debian debian_linux 8.0 cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
opensuse leap 15.0 cpe:2.3:o:opensuse:leap:15.0:*:*:*:*:*:*:*
opensuse leap 15.1 cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:*
redhat mrg_realtime 2.0 cpe:2.3:a:redhat:mrg_realtime:2.0:*:*:*:*:*:*:*
redhat virtualization_host_eus 4.2 cpe:2.3:a:redhat:virtualization_host_eus:4.2:*:*:*:*:*:*:*
redhat enterprise_linux 8.0 cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
redhat enterprise_linux_aus 7.5 cpe:2.3:o:redhat:enterprise_linux_aus:7.5:*:*:*:*:*:*:*
redhat enterprise_linux_eus 7.6 cpe:2.3:o:redhat:enterprise_linux_eus:7.6:*:*:*:*:*:*:*
redhat enterprise_linux_eus 7.7 cpe:2.3:o:redhat:enterprise_linux_eus:7.7:*:*:*:*:*:*:*
redhat enterprise_linux_eus 8.1 cpe:2.3:o:redhat:enterprise_linux_eus:8.1:*:*:*:*:*:*:*
redhat enterprise_linux_eus 8.2 cpe:2.3:o:redhat:enterprise_linux_eus:8.2:*:*:*:*:*:*:*
redhat enterprise_linux_eus 8.4 cpe:2.3:o:redhat:enterprise_linux_eus:8.4:*:*:*:*:*:*:*
redhat enterprise_linux_for_real_time 7 cpe:2.3:o:redhat:enterprise_linux_for_real_time:7:*:*:*:*:*:*:*
redhat enterprise_linux_for_real_time 8 cpe:2.3:o:redhat:enterprise_linux_for_real_time:8:*:*:*:*:*:*:*
redhat enterprise_linux_for_real_time_eus 8.2 cpe:2.3:o:redhat:enterprise_linux_for_real_time_eus:8.2:*:*:*:*:*:*:*
redhat enterprise_linux_for_real_time_eus 8.4 cpe:2.3:o:redhat:enterprise_linux_for_real_time_eus:8.4:*:*:*:*:*:*:*
redhat enterprise_linux_for_real_time_for_nfv 7 cpe:2.3:o:redhat:enterprise_linux_for_real_time_for_nfv:7:*:*:*:*:*:*:*
redhat enterprise_linux_for_real_time_for_nfv 8 cpe:2.3:o:redhat:enterprise_linux_for_real_time_for_nfv:8:*:*:*:*:*:*:*
redhat enterprise_linux_for_real_time_for_nfv_eus 8.2 cpe:2.3:o:redhat:enterprise_linux_for_real_time_for_nfv_eus:8.2:*:*:*:*:*:*:*
redhat enterprise_linux_for_real_time_for_nfv_eus 8.4 cpe:2.3:o:redhat:enterprise_linux_for_real_time_for_nfv_eus:8.4:*:*:*:*:*:*:*
redhat enterprise_linux_server 7.0 cpe:2.3:o:redhat:enterprise_linux_server:7.0:*:*:*:*:*:*:*
redhat enterprise_linux_server_aus 7.3 cpe:2.3:o:redhat:enterprise_linux_server_aus:7.3:*:*:*:*:*:*:*
redhat enterprise_linux_server_aus 7.4 cpe:2.3:o:redhat:enterprise_linux_server_aus:7.4:*:*:*:*:*:*:*
redhat enterprise_linux_server_aus 7.6 cpe:2.3:o:redhat:enterprise_linux_server_aus:7.6:*:*:*:*:*:*:*
redhat enterprise_linux_server_aus 7.7 cpe:2.3:o:redhat:enterprise_linux_server_aus:7.7:*:*:*:*:*:*:*
redhat enterprise_linux_server_aus 8.2 cpe:2.3:o:redhat:enterprise_linux_server_aus:8.2:*:*:*:*:*:*:*
redhat enterprise_linux_server_aus 8.4 cpe:2.3:o:redhat:enterprise_linux_server_aus:8.4:*:*:*:*:*:*:*
redhat enterprise_linux_server_tus 7.3 cpe:2.3:o:redhat:enterprise_linux_server_tus:7.3:*:*:*:*:*:*:*
redhat enterprise_linux_server_tus 7.4 cpe:2.3:o:redhat:enterprise_linux_server_tus:7.4:*:*:*:*:*:*:*
redhat enterprise_linux_server_tus 7.6 cpe:2.3:o:redhat:enterprise_linux_server_tus:7.6:*:*:*:*:*:*:*
redhat enterprise_linux_server_tus 7.7 cpe:2.3:o:redhat:enterprise_linux_server_tus:7.7:*:*:*:*:*:*:*
redhat enterprise_linux_server_tus 8.2 cpe:2.3:o:redhat:enterprise_linux_server_tus:8.2:*:*:*:*:*:*:*
redhat enterprise_linux_server_tus 8.4 cpe:2.3:o:redhat:enterprise_linux_server_tus:8.4:*:*:*:*:*:*:*
redhat enterprise_linux_tus 7.6 cpe:2.3:o:redhat:enterprise_linux_tus:7.6:*:*:*:*:*:*:*
huawei alp-al00b_firmware < 9.1.0.333\(c00e333r2p1t8\) cpe:2.3:o:huawei:alp-al00b_firmware:*:*:*:*:*:*:*:*
huawei ares-al00b_firmware < 9.1.0.160\(c00e160r2p5t8\) cpe:2.3:o:huawei:ares-al00b_firmware:*:*:*:*:*:*:*:*
huawei ares-al10d_firmware < 9.1.0.160\(c00e160r2p5t8\) cpe:2.3:o:huawei:ares-al10d_firmware:*:*:*:*:*:*:*:*
huawei ares-tl00c_firmware < 9.1.0.165\(c01e165r2p5t8\) cpe:2.3:o:huawei:ares-tl00c_firmware:*:*:*:*:*:*:*:*
huawei asoka-al00ax_firmware < 9.1.1.181\(c00e48r6p1\) cpe:2.3:o:huawei:asoka-al00ax_firmware:*:*:*:*:*:*:*:*
huawei atomu-l33_firmware < 8.0.0.147\(c605custc605d1\) cpe:2.3:o:huawei:atomu-l33_firmware:*:*:*:*:*:*:*:*
huawei atomu-l41_firmware < 8.0.0.153\(c461custc461d1\) cpe:2.3:o:huawei:atomu-l41_firmware:*:*:*:*:*:*:*:*
huawei atomu-l42_firmware < 8.0.0.155\(c636custc636d1\) cpe:2.3:o:huawei:atomu-l42_firmware:*:*:*:*:*:*:*:*
huawei bla-al00b_firmware < 9.1.0.329\(c786e320r2p1t8\) cpe:2.3:o:huawei:bla-al00b_firmware:*:*:*:*:*:*:*:*
huawei bla-l29c_firmware < 9.1.0.300\(c605e2r1p12t8\) cpe:2.3:o:huawei:bla-l29c_firmware:*:*:*:*:*:*:*:*
huawei bla-tl00b_firmware < 9.1.0.329\(c01e320r1p1t8\) cpe:2.3:o:huawei:bla-tl00b_firmware:*:*:*:*:*:*:*:*
huawei barca-al00_firmware < 8.0.0.366\(c00\) cpe:2.3:o:huawei:barca-al00_firmware:*:*:*:*:*:*:*:*
huawei berkeley-al20_firmware < 9.1.0.333\(c00e333r2p1t8\) cpe:2.3:o:huawei:berkeley-al20_firmware:*:*:*:*:*:*:*:*
huawei berkeley-l09_firmware < 9.1.0.332\(c432e5r1p13t8\) cpe:2.3:o:huawei:berkeley-l09_firmware:*:*:*:*:*:*:*:*
huawei berkeley-tl10_firmware < 9.1.0.333\(c01e333r1p1t8\) cpe:2.3:o:huawei:berkeley-tl10_firmware:*:*:*:*:*:*:*:*
huawei cairogo-l22_firmware < cairogo-l22c461b153 cpe:2.3:o:huawei:cairogo-l22_firmware:*:*:*:*:*:*:*:*
huawei charlotte-l29c_firmware < 9.1.0.311\(c605e2r1p11t8\) cpe:2.3:o:huawei:charlotte-l29c_firmware:*:*:*:*:*:*:*:*
huawei columbia-al10b_firmware < 9.1.0.333\(c00e333r1p1t8\) cpe:2.3:o:huawei:columbia-al10b_firmware:*:*:*:*:*:*:*:*
huawei columbia-al10i_firmware < 9.1.0.335\(c675e8r1p9t8\) cpe:2.3:o:huawei:columbia-al10i_firmware:*:*:*:*:*:*:*:*
huawei columbia-l29d_firmware < 9.1.0.350\(c10e5r1p14t8\) cpe:2.3:o:huawei:columbia-l29d_firmware:*:*:*:*:*:*:*:*
huawei columbia-tl00d_firmware < 8.1.0.186\(c01gt\) cpe:2.3:o:huawei:columbia-tl00d_firmware:*:*:*:*:*:*:*:*
huawei cornell-al00a_firmware < 9.1.0.333\(c00e333r1p1t8\) cpe:2.3:o:huawei:cornell-al00a_firmware:*:*:*:*:*:*:*:*
huawei cornell-al00i_firmware < 9.1.0.363\(c675e3r1p9t8\) cpe:2.3:o:huawei:cornell-al00i_firmware:*:*:*:*:*:*:*:*
huawei cornell-al00ind_firmware < 8.2.0.141\(c675custc675d1gt\) cpe:2.3:o:huawei:cornell-al00ind_firmware:*:*:*:*:*:*:*:*
huawei cornell-al10ind_firmware < 9.1.0.363\(c675e2r1p9t8\) cpe:2.3:o:huawei:cornell-al10ind_firmware:*:*:*:*:*:*:*:*
huawei cornell-l29a_firmware < 9.1.0.336\(c636e2r1p12t8\) cpe:2.3:o:huawei:cornell-l29a_firmware:*:*:*:*:*:*:*:*
huawei cornell-tl10b_firmware < 9.1.0.333\(c01e333r1p1t8\) cpe:2.3:o:huawei:cornell-tl10b_firmware:*:*:*:*:*:*:*:*
huawei dubai-al00a_firmware < 8.2.0.190\(c00r2p2\) cpe:2.3:o:huawei:dubai-al00a_firmware:*:*:*:*:*:*:*:*
huawei dura-al00a_firmware < 1.0.0.182\(c00\) cpe:2.3:o:huawei:dura-al00a_firmware:*:*:*:*:*:*:*:*
huawei dura-tl00a_firmware < 1.0.0.176\(c01\) cpe:2.3:o:huawei:dura-tl00a_firmware:*:*:*:*:*:*:*:*
huawei emily-l29c_firmware 8.1.0.156\(c605\) cpe:2.3:o:huawei:emily-l29c_firmware:8.1.0.156\(c605\):*:*:*:*:*:*:*
huawei ever-l29b_firmware < 9.1.0.338\(c185e3r3p1\) cpe:2.3:o:huawei:ever-l29b_firmware:*:*:*:*:*:*:*:*
huawei figo-l23_firmware < 9.1.0.160\(c605e6r1p5t8\) cpe:2.3:o:huawei:figo-l23_firmware:*:*:*:*:*:*:*:*
huawei figo-l31_firmware 8.0.0.122d\(c652\) cpe:2.3:o:huawei:figo-l31_firmware:8.0.0.122d\(c652\):*:*:*:*:*:*:*
huawei figo-tl10b_firmware < 9.1.0.130\(c01e115r2p8t8\) cpe:2.3:o:huawei:figo-tl10b_firmware:*:*:*:*:*:*:*:*
huawei florida-al20b_firmware < 9.1.0.128\(c00e112r1p6t8\) cpe:2.3:o:huawei:florida-al20b_firmware:*:*:*:*:*:*:*:*

References for CVE-2019-9506

URL Tags
http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00036.html Mailing List Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00037.html Mailing List Third Party Advisory
http://seclists.org/fulldisclosure/2019/Aug/11 Mailing List Third Party Advisory
http://seclists.org/fulldisclosure/2019/Aug/13 Mailing List Third Party Advisory
http://seclists.org/fulldisclosure/2019/Aug/14 Mailing List Third Party Advisory
http://seclists.org/fulldisclosure/2019/Aug/15 Mailing List Third Party Advisory
http://www.cs.ox.ac.uk/publications/publication12404-abstract.html Third Party Advisory
http://www.huawei.com/en/psirt/security-advisories/huawei-sa-20190828-01-knob-en Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:2975 Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:3055 Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:3076 Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:3089 Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:3165 Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:3187 Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:3217 Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:3218 Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:3220 Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:3231 Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:3309 Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:3517 Third Party Advisory
https://access.redhat.com/errata/RHSA-2020:0204 Third Party Advisory
https://lists.debian.org/debian-lts-announce/2019/09/msg00014.html Mailing List Third Party Advisory
https://lists.debian.org/debian-lts-announce/2019/09/msg00015.html Mailing List Third Party Advisory
https://lists.debian.org/debian-lts-announce/2019/09/msg00025.html Mailing List Third Party Advisory
https://usn.ubuntu.com/4115-1/ Third Party Advisory
https://usn.ubuntu.com/4118-1/ Third Party Advisory
https://usn.ubuntu.com/4147-1/ Third Party Advisory
https://www.bluetooth.com/security/statement-key-negotiation-of-bluetooth/ Third Party Advisory
https://www.kb.cert.org/vuls/id/918987/ Third Party Advisory US Government Resource
https://www.usenix.org/conference/usenixsecurity19/presentation/antonioli Third Party Advisory
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