Missing doorbell ring in Linux fbnic driver after dropped packet
Key facts
- Attack vector
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- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
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- Confidentiality · integrity · availability
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- Fix status
- Fixed
No CVSS vector from any source. Fix status from CNA.
Summary
The Linux kernel fbnic Ethernet driver, from 6.11 onward, is affected. When the last packet of a transmit burst is dropped in fbnic_tx_map(), the driver never rings the doorbell, so packets already queued stay invisible to the hardware until the next transmit on that queue. A burst followed by idle traffic may therefore never be sent.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
In the Linux kernel, the following vulnerability has been resolved: eth: fbnic: ring the doorbell if a burst ends in a drop fbnic_tx_map() skips the doorbell write, and the completion request, for every packet handed to it with xmit_more set, counting on the packet which ends the burst to publish them all. When that packet is dropped instead - skb_put_padto(), skb_cow_head() or a DMA mapping failure - nothing rings. The descriptors of the preceding packets stay invisible to the HW until the next transmit on that queue, which for a burst-then-idle workload may never come. Remember the meta descriptor of the last packet left without a doorbell and flush it from the error paths. The completion request has to be set on that descriptor rather than simply writing the tail, otherwise the HW would transmit the packets but never report a head, and the ring would fill up and stall for good. This is very similar to Joe's recent series of fixes for bnxt. Not seen in real life, reproduced under QEMU with failure injection.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
Upgrade the Linux kernel to 6.18.54, 7.2.8 or 7.3, whichever matches the installed release branch.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA Linux (Linux) Fixed in 6.18.54, 7.2.8, 7.3
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
Not affected: 7 products
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat OpenShift Container Platform 4
- Red Hat OpenShift Container Platform 5
Timeline
- 2026-10-06 Threatist record created from CVE-2026-98277
- 2026-10-06 Alias added: GHSA-xjm7-64jw-75jr
- 2026-10-11 Affected versions changed · Red Hat
- 2026-10-11 CVSS score added · Red Hat
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-11-06 Affected versions changed · Red Hat
References
More Linux vulnerabilities
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- TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
Sources
- CVE-2026-98277 · CVE Program
- CVE-2026-98277 · NVD
- FIRST EPSS
- GHSA-xjm7-64jw-75jr · GitHub Advisory Database · CC BY 4.0
- CVE-2026-98277 · Red Hat security data · CC BY 4.0
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