CVE-2026-64537

Received Received - Intake

Bridge CFM Configuration Interval Validation Flaw

Publication date: 2026-07-27

Last updated on: 2026-07-27

Assigner: kernel.org

Description

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).

CVSS Scores

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Meta Information

Published

2026-07-27

Last Modified

2026-07-27

Generated

2026-08-17

AI Q&A

2026-07-28

EPSS Evaluated

2026-08-15

NVD

CVE-2026-64537

EUVD

EUVD-2026-49588

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	From 3.3 (inc) to 10.0 (inc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel involves a flaw in the bridge CFM (Connectivity Fault Management) component. When an invalid CCM interval is set, the system enters a tight loop that rapidly allocates memory until it runs out, causing a denial of service.

Detection Guidance

This vulnerability may cause high CPU usage or memory exhaustion due to a tight loop in the Linux kernel's bridge CFM module. Monitor for unexpected high CPU usage or OOM conditions in kernel processes. Check kernel logs for bridge CFM-related errors or warnings.

Impact Analysis

This vulnerability can cause system instability or crashes due to excessive memory allocation. It may lead to degraded performance or complete unavailability of affected services relying on the Linux kernel.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards as it pertains to a Linux kernel bridge CFM configuration issue causing OOM conditions. No evidence suggests data breaches or unauthorized access risks that would impact regulatory compliance.

Mitigation Strategies

Update the Linux kernel to a patched version that includes the fix for this vulnerability. If immediate patching is not possible, disable the bridge CFM feature by removing or blacklisting the bridge module until the patch is applied.

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