net: openvswitch: conntrack: avoid modifying shared unconfirmed ct entry
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 6 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.
Summary
In the Linux kernel's Open vSwitch conntrack code, an skb carrying an unconfirmed conntrack entry can be cloned, and both clones may then be committed with different extension sets. The first clone links the extension pointer into the expectation list, then loses confirmation, and the second clone adds a new extension that breaks that pointer, leading to a use-after-free on destruction. An attacker with local access and low privileges can trigger a memory-corruption condition with high impact to confidentiality, integrity and availability (CVSS 3.1 7.8, HIGH). Red Hat rates it Moderate.
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: openvswitch: conntrack: avoid modifying shared unconfirmed ct entry In a case where skb with an unconfirmed ct entry gets cloned, we may end up committing both but with different sets of extensions. The series of events: 1. The first clone wants to commit and runs the helpers wiring up the extension pointer into the expectation list. 2. Then it looses the confirmation keeping the entry unconfirmed. 3. Second clone now wants to commit labels and adds the new extension for that breaking the pointer in the expectation list causing UAF on the destruction path later. While this is possible to trigger, there should be no practical network pipeline where committing both clones without modifications into the same zone is needed. So, let's just reset the entry in case for some reason we got an skb with a shared one during commit. This doesn't affect any known use cases, but avoids any potential problems with sharing and modification of the unconfirmed ct entry. The fixes tag points to the introduction of helpers, since that's the main UAF trigger for the sharing.
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 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, 6.18.55, 7.2.9 or 7.3, or a later release on the same branch. The upstream fix resets the entry when a shared unconfirmed conntrack entry reaches commit, so no code change is needed in configurations that do not commit cloned skbs. Red Hat Enterprise Linux 7, 8, 9 and 10 and OpenShift Container Platform 4 and 5 have no fix available yet.
Written with Claude Haiku 5.5 from the sources below · 2026-10-30
- Fix · CNA Linux (Linux) Fixed in 5.10.271, 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 |
| Red Hat Enterprise Linux 7 | Affected | No fix yet |
| Red Hat Enterprise Linux 8 | Affected | No fix yet |
| Red Hat Enterprise Linux 9 | Affected | No fix yet |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet |
Not affected: 1 product
- Red Hat Enterprise Linux 6
Timeline
- 2026-10-18 Threatist record created from CVE-2026-98491
- 2026-10-18 Alias added: GHSA-xf3m-wp4c-wrgw
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-21 Affected versions changed · Red Hat
- 2026-10-21 CVSS score added · Red Hat
- 2026-10-24 CVSS score added · CNA
- 2026-10-30 Affected versions changed · Red Hat
References
Other 8
- https://git.kernel.org/stable/c/e0fa5ea434b7e8467ef3adc64e3858b1ca2a642d
- https://git.kernel.org/stable/c/37e3c878b183a115f9a114067f9ef3b408ad27fb
- https://git.kernel.org/stable/c/707c2dc77891a874f4e8c52c285a511079164ec8
- https://git.kernel.org/stable/c/de41ee24f77b0fc45397db3e277cae2adbd43dfe
- https://git.kernel.org/stable/c/55e5256adf3940e71802e2f749cacf81518726b0
- https://git.kernel.org/stable/c/e2829ae5459ddb5fce526b2e84697edf6c0c3cef
- https://git.kernel.org/stable/c/457e0df1b5711fbeb7ba1b6bfd826f5ef30e7e55
- https://git.kernel.org/stable/c/26b2bd70d22457556e2fa01cbf1192cb1a94d619
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Sources
- CVE-2026-98491 · CVE Program
- CVE-2026-98491 · NVD
- FIRST EPSS
- GHSA-xf3m-wp4c-wrgw · GitHub Advisory Database · CC BY 4.0
- CVE-2026-98491 · 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