Use-after-free in Linux kernel SMC link group list traversal
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
- Partial Red Hat: 5 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
The Linux kernel from 5.8 is affected. In the SMC networking code, smcr_port_err() walks the link group list without holding its lock, so a concurrent link group termination can free an entry that is still being used. This results in a use-after-free in the kernel.
Written with Claude Haiku 5.5 from the sources below · 2026-10-30
Description from the CNA
In the Linux kernel, the following vulnerability has been resolved: net/smc: fix UAF on lgr list traversal in smcr_port_err() smcr_port_err() traverses smc_lgr_list.list without holding smc_lgr_list.lock, allowing a concurrent smc_lgr_terminate_sched() to free an lgr while it is still being dereferenced. Hold smc_lgr_list.lock across the traversal. Update smc_ib_gid_check() to call smcr_port_err() after releasing the lock.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
Update the Linux kernel to 5.15.222, 6.1.189, 6.6.158, 6.12.112, 6.18.55, 7.2.9 or 7.3, depending on the stable branch in use. Red Hat lists Red Hat Enterprise Linux 8, 9 and 10 and Red Hat OpenShift Container Platform 4 and 5 as affected with no fix available.
Written with Claude Haiku 5.5 from the sources below · 2026-10-30
- Fix · CNA Linux (Linux) Fixed in 5.15.222, 6.1.189, 6.6.158, 6.12.112, 6.18.55, 7.2.9, 7.3
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
Not affected: 2 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
Timeline
- 2026-10-18 Threatist record created from CVE-2026-98559
- 2026-10-18 Alias added: GHSA-4x5q-83g5-68jv
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-20 Affected versions changed · Red Hat
- 2026-10-20 CVSS score added · Red Hat
- 2026-10-30 Affected versions changed · Red Hat
References
Other 7
- https://git.kernel.org/stable/c/34bcf11cd2528ae00bb6d764d808083c66824277
- https://git.kernel.org/stable/c/0edcc4284392b28826b5d37532b366b291e6e0fa
- https://git.kernel.org/stable/c/00a59600ae72d24859d0ad1783a78bc921bc2599
- https://git.kernel.org/stable/c/3d35f069e1c119992000d51236dbe54da2d4e61e
- https://git.kernel.org/stable/c/3d65a2eb4449fc9658fb860dea893025d028d90e
- https://git.kernel.org/stable/c/a9b968e42690d784c241a0761c10253271f7df5d
- https://git.kernel.org/stable/c/61cb282fe97b3b0ba32ca09417a693162bf4ae3f
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Sources
- CVE-2026-98559 · CVE Program
- CVE-2026-98559 · NVD
- FIRST EPSS
- GHSA-4x5q-83g5-68jv · GitHub Advisory Database · CC BY 4.0
- CVE-2026-98559 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences