Linux Kernel up to 6.18.39/7.1.4/7.2-rc2 Bluetooth L2CAP l2cap_put_ident allocation of resources

CVSS Meta Temp Score
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CTI Interest Score
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7.2$0-$5k0.00+

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.18.39/7.1.4/7.2-rc2. It has been declared as critical. Affected is the function l2cap_put_ident of the component Bluetooth L2CAP. Executing a manipulation can lead to allocation of resources. This vulnerability appears as CVE-2026-72333. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 6.18.39/7.1.4/7.2-rc2 and classified as critical. This vulnerability affects the function l2cap_put_ident of the component Bluetooth L2CAP. The manipulation with an unknown input leads to a allocation of resources vulnerability. The CWE definition for the vulnerability is CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. As an impact it is known to affect availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: fix tx ident leak for commands without a response Commit 6c3ea155e5ee ("Bluetooth: L2CAP: Fix not tracking outstanding TX ident") changed ident allocation to use an IDA, releasing idents in l2cap_put_ident() when the matching response command is received. But identifiers allocated for commands that have no response defined are never released. In particular L2CAP_LE_CREDITS is sent repeatedly for the lifetime of an LE CoC channel, so a peer streaming data to the host exhausts the 1-255 ident range after 254 credit packets. From then on l2cap_get_ident() fails: kernel: Bluetooth: Unable to allocate ident: -28 and every subsequent L2CAP_LE_CREDITS packet is sent with ident 0, which is invalid (Core Spec, Vol 3, Part A, Section 4: "Signaling identifier 0x00 is an invalid identifier and shall never be used in any command"). Remote stacks that validate the ident drop these commands, never receive new credits, and the channel stalls permanently. With default socket buffers this happens after roughly 0.5 MB of received data (the exact amount depends on the socket receive buffer): < ACL Data TX: Handle 2048 flags 0x00 dlen 12 LE L2CAP: LE Flow Control Credit (0x16) ident 0 len 4 Source CID: 64 Credits: 1 Release the ident immediately after sending L2CAP_LE_CREDITS since no response will ever release it. Use a local variable instead of chan->ident so that an ident that an EXT_FLOWCTL channel may be waiting on (e.g. a pending reconfigure) is not overwritten by a credit packet. Also add the missing L2CAP_LE_CONN_RSP case to l2cap_put_ident() so idents allocated for outgoing L2CAP_LE_CONN_REQ commands are released when the response arrives.

The advisory is shared for download at git.kernel.org. This vulnerability was named CVE-2026-72333 since 08/09/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 08/15/2026). The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 6.18.40, 7.1.5 or 7.2-rc3 eliminates this vulnerability. Applying the patch b8a32a5fc915b024c60f18d51b6cffd2bd64d4a6/bd1e01170341291292fd4c46b5f6949da282ca6c/0c602cb8f148a36bfb39c25ade400bdadc023c4f/d0a2b0c81f112540a337cde1c20251bf05ddf1da/6e1930ece855a4c256f1c7e6632d634cfb9888b5 is able to eliminate this problem.

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Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.5
VulDB Meta Temp Score: 7.2

VulDB Base Score: 7.5
VulDB Temp Score: 7.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Allocation of resources
CWE: CWE-770 / CWE-400 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.18.40/7.1.5/7.2-rc3
Patch: b8a32a5fc915b024c60f18d51b6cffd2bd64d4a6/bd1e01170341291292fd4c46b5f6949da282ca6c/0c602cb8f148a36bfb39c25ade400bdadc023c4f/d0a2b0c81f112540a337cde1c20251bf05ddf1da/6e1930ece855a4c256f1c7e6632d634cfb9888b5

Timelineinfo

08/09/2026 CVE reserved
08/15/2026 +6 days Advisory disclosed
08/15/2026 +0 days VulDB entry created
08/15/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-72333 (🔒)
GCVE (CVE): GCVE-0-2026-72333
GCVE (VulDB): GCVE-100-390928

Entryinfo

Created: 08/15/2026 16:22
Changes: 08/15/2026 16:22 (59)
Complete: 🔍
Cache ID: 216::103

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