CVE-2021-1957

Service interruption via retained unencrypted ACL link

Published Sep 9, 2021 · Updated Aug 3, 2024

Improper access control in Qualcomm Snapdragon Bluetooth firmware allows physically proximate attackers to interrupt device service. During reconnection with a paired device after ACL link encryption fails, the Bluetooth component retains the ACL link instead of disconnecting it. Exploitation requires adjacent Bluetooth access and an existing pairing relationship; the published impact is limited to loss of availability.

CVSS severity6.5
Medium
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in Qualcomm Snapdragon Bluetooth firmware allows physically proximate attackers to interrupt device service. During reconnection with a paired device after ACL link encryption fails, the Bluetooth component retains the ACL link instead of disconnecting it. Exploitation requires adjacent Bluetooth access and an existing pairing relationship; the published impact is limited to loss of availability.

The record

CVE
CVE-2021-1957
Published
Sep 9, 2021
Updated
Aug 3, 2024
Vendor
Qualcomm
Product
Snapdragon
Classifications
T1499.004
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 9, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=APQ8017, QCA6174A, QCA6390, QCA6391, QCA6421, QCA6426, QCA6431, QCA6436, QCA6574AU, QCA6696, QCM6125, QCS610, QCS6125, QRB5165, Qualcomm215, SA6145P, SA6150P, SA6155P, SA8145P, SA8150P, SA8155P, SA8195P, SD855, SD865 5G, SD870, SDX55, SDX55M, SDXR2 5G, WCD9326, WCD9335, WCD9341, WCD9370, WCD9380, WCD9385, WCN3610, WCN3615, WCN3660B, WCN3680, WCN3950, WCN3980, WCN3990, WCN3998, WCN6850, WCN6851, WSA8810, WSA8815

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Qualcomm · Snapdragonversion=APQ8017, QCA6174A, QCA6390, QCA6391, QCA6421, QCA6426, QCA6431, QCA6436, QCA6574AU, QCA6696, QCM6125, QCS610, QCS6125, QRB5165, Qualcomm215, SA6145P, SA6150P, SA6155P, SA8145P, SA8150P, SA8155P, SA8195P, SD855, SD865 5G, SD870, SDX55, SDX55M, SDXR2 5G, WCD9326, WCD9335, WCD9341, WCD9370, WCD9380, WCD9385, WCN3610, WCN3615, WCN3660B, WCN3680, WCN3950, WCN3980, WCN3990, WCN3998, WCN6850, WCN6851, WSA8810, WSA8815

Published CVSS scores

3.3NIST NVDAV:A/AC:L/Au:N/C:N/I:N/A:P
6.5Qualcomm, Inc.CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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