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CVE-2026-64537· NVD / CVE Program· CNA Linux

bridge: cfm: reject invalid CCM interval at configuration time

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).

—No exploit Fix available
Published
Jul 27, 2026
Updated
Aug 17, 2026
EPSS
0.2% · 6th percentile
CWE
—
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Action score

0

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Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

Affected systems

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Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 5.11affected
    • 2be665c3940d367e0a2a8128eb4985ce323f99a3 and later · before 2870056a78961e0fecd652362ee9d3fcfd24a8a6affected · git
    • 2be665c3940d367e0a2a8128eb4985ce323f99a3 and later · before f0f5eb59a97ece0d85de8cfa95dc18c609302a8baffected · git
    • 2be665c3940d367e0a2a8128eb4985ce323f99a3 and later · before 53788b134519e995699ea3721969c96a08d64575affected · git
    • 2be665c3940d367e0a2a8128eb4985ce323f99a3 and later · before b42aeb58317f12024734759ff745856b53948873affected · git
    • 2be665c3940d367e0a2a8128eb4985ce323f99a3 and later · before a090880c1f544589427e5b7050c40fb211ccecb4affected · git
    • 2be665c3940d367e0a2a8128eb4985ce323f99a3 and later · before 865643640b5b5c4579b32d7a55ac9ad648362eaaaffected · git
    • 2be665c3940d367e0a2a8128eb4985ce323f99a3 and later · before f3e02edd8322b31b8e6517faa6ba053bf29d1e26affected · git
    • before 5.11not affected · semver
    • 5.15.212 and later · up to and including 5.15.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.180-16.1.180-1
Debian:12linux-6.12before 6.12.100-1~deb12u16.12.100-1~deb12u1
Debian:13linuxbefore 6.12.100-16.12.100-1
Debian:14linuxbefore 7.1.5-17.1.5-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan
  • CVE-2026-74309vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
    40Plan
  • CVE-2026-74280crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
    40Plan
  • CVE-2026-74279crypto: cavium/cpt - fix DMA cleanup using wrong loop index
    40Plan

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux2870056a78961e0fecd652362ee9d3fcfd24a8a6Vendor (CNA)
Linux Linux53788b134519e995699ea3721969c96a08d64575Vendor (CNA)
Linux Linux865643640b5b5c4579b32d7a55ac9ad648362eaaVendor (CNA)
Linux Linuxa090880c1f544589427e5b7050c40fb211ccecb4Vendor (CNA)
Linux Linuxb42aeb58317f12024734759ff745856b53948873Vendor (CNA)
Linux Linuxf0f5eb59a97ece0d85de8cfa95dc18c609302a8bVendor (CNA)
Linux Linuxf3e02edd8322b31b8e6517faa6ba053bf29d1e26Vendor (CNA)
debian:linux6.1.180-1 · Debian:12Package registry (OSV)
debian:linux-6.126.12.100-1~deb12u1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

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No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

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No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

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Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

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Change log

  1. Fix✗ → ✓

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References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

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