Linux Kernel up to 7.1.4 bridge net/bridge/br_cfm.c br_cfm_cc_ccm_tx exp_interval allocation of resources

CVSS Meta Temp Score
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CTI Interest Score
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4.3$0-$5k1.40

Summaryinfo

A vulnerability categorized as problematic has been discovered in Linux Kernel up to 7.1.4. Impacted is the function br_cfm_cc_ccm_tx of the file net/bridge/br_cfm.c of the component bridge. Executing a manipulation of the argument exp_interval can lead to allocation of resources. This vulnerability appears as CVE-2026-64537. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability classified as problematic was found in Linux Kernel up to 7.1.4. This vulnerability affects the function br_cfm_cc_ccm_tx of the file net/bridge/br_cfm.c of the component bridge. The manipulation of the argument exp_interval 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: bridge: cfm: reject invalid CCM interval at configuration time ccm_tx_work_expired() re-arms itself via queue_delayed_work() using the configured exp_interval converted by interval_to_us(). When exp_interval is BR_CFM_CCM_INTERVAL_NONE or out of range, interval_to_us() returns 0, causing the worker to fire immediately in a tight loop that allocates skbs until OOM. Fix this by validating exp_interval at configuration time: - Constrain IFLA_BRIDGE_CFM_CC_CONFIG_EXP_INTERVAL to the valid range [BR_CFM_CCM_INTERVAL_3_3_MS, BR_CFM_CCM_INTERVAL_10_MIN] in the netlink policy so userspace cannot set an invalid value. - Reject starting CCM TX in br_cfm_cc_ccm_tx() when exp_interval has not yet been configured (defaults to 0 from kzalloc).

The advisory is shared for download at git.kernel.org. This vulnerability was named CVE-2026-64537 since 07/19/2026. The exploitation appears to be easy. The attack can be initiated remotely. Additional levels of successful authentication are necessary for exploitation. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 5.15.212, 6.1.178, 6.6.145, 6.12.97, 6.18.40, 7.1.5 or 7.2-rc1 eliminates this vulnerability. Applying the patch 2870056a78961e0fecd652362ee9d3fcfd24a8a6/f0f5eb59a97ece0d85de8cfa95dc18c609302a8b/53788b134519e995699ea3721969c96a08d64575/b42aeb58317f12024734759ff745856b53948873/a090880c1f544589427e5b7050c40fb211ccecb4/865643640b5b5c4579b32d7a55ac9ad648362eaa/f3e02edd8322b31b8e6517faa6ba053bf29d1e26 is able to eliminate this problem.

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Productinfo

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Version

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.5
VulDB Meta Temp Score: 4.3

VulDB Base Score: 4.5
VulDB Temp Score: 4.3
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 5.15.212/6.1.178/6.6.145/6.12.97/6.18.40/7.1.5/7.2-rc1
Patch: 2870056a78961e0fecd652362ee9d3fcfd24a8a6/f0f5eb59a97ece0d85de8cfa95dc18c609302a8b/53788b134519e995699ea3721969c96a08d64575/b42aeb58317f12024734759ff745856b53948873/a090880c1f544589427e5b7050c40fb211ccecb4/865643640b5b5c4579b32d7a55ac9ad648362eaa/f3e02edd8322b31b8e6517faa6ba053bf29d1e26

Timelineinfo

07/19/2026 CVE reserved
07/27/2026 +8 days Advisory disclosed
07/27/2026 +0 days VulDB entry created
07/27/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-64537 (🔒)
GCVE (CVE): GCVE-0-2026-64537
GCVE (VulDB): GCVE-100-383608

Entryinfo

Created: 07/27/2026 23:27
Changes: 07/27/2026 23:27 (61)
Complete: 🔍
Cache ID: 216::103

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