Improper flag filtering in Linux kernel IPVS backup server
Key facts
- Attack vector
- —
- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
- —
- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 7 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
The Linux kernel IPVS synchronization protocol does not filter some connection flags received by the backup server. Crafted messages with a NO_CPORT and TEMPLATE flag combination, or an unexpected ONE_PACKET flag, can break connection handling on the backup server.
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: ipvs: filter some flags received in the backup server While the IPVS SYNC protocol is not secure by design we can still protect the backup server from messages that can wreak havoc. This commit addresses problems from received connection flags or their combinations. We now drop messages as follows: 1. the NO_CPORT+TEMPLATE combination allows lookups for normal connections to hit template which can break in many ways. While the master does not sync connections with NO_CPORT flag, i.e. before they are established, we still accept NO_CPORT without TEMPLATE. 2. ONE_PACKET: it is not sent by master, so we do not expect it in backup. Before now it was ignored by IP_VS_CONN_F_BACKUP_MASK for protocol v1 while protocol v0 created connections that are not hashed and dropped immediately. Better to apply the IP_VS_CONN_F_BACKUP_MASK also to the flags from v0 messages for consistency with v1.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 2.6.14 and later | 5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.113, 6.18.56, 7.2.10, 7.3 | Patch available | CNA |
- Linux VendorLinux Affected 2.6.14 and later Fixed in 5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.113, 6.18.56, 7.2.10, 7.3 Patch available CNA
Remediation
Upgrade the Linux kernel to 5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.113, 6.18.56, 7.2.10 or 7.3. The sources list no fixed version for Red Hat Enterprise Linux 6, 7, 8, 9 and 10 or OpenShift Container Platform 4 and 5.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA Linux (Linux) Fixed in 5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.113, 6.18.56, 7.2.10, 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 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 7 | 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 |
Timeline
- 2026-10-18 Threatist record created from CVE-2026-98794
- 2026-10-18 Alias added: GHSA-c8w6-8f9f-2m9q
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-21 Fix available: Linux/[email protected], Linux/Linux@d7d33c9efa9d1a2f244a1a64ec9b540b0f8975a0 · CNA
- 2026-10-21 1 new reference · CNA
- 2026-10-24 Affected versions changed · Red Hat
- 2026-10-24 CVSS score added · Red Hat
- 2026-10-30 Fix available: Linux/Linux@3a9f5459db60311643bfbadf019f6d5370f2f26a, Linux/Linux@438a5335276614186d6a96b8e7bddce811ad4ad6, Linux/[email protected] +3 · CNA
- 2026-10-30 3 new references · CNA
- 2026-11-06 Affected versions changed · Red Hat
References
Other 8
- https://git.kernel.org/stable/c/ef3cd6c0b826e50dc21653b32552e258de6fd51c
- https://git.kernel.org/stable/c/3a9f5459db60311643bfbadf019f6d5370f2f26a
- https://git.kernel.org/stable/c/438a5335276614186d6a96b8e7bddce811ad4ad6
- https://git.kernel.org/stable/c/d7d33c9efa9d1a2f244a1a64ec9b540b0f8975a0
- https://git.kernel.org/stable/c/f4cd1db7d421e82945713a36084bb0c35b75b27e
- https://git.kernel.org/stable/c/55d033324f67a15ff56be6d38d6e87f644e0ed62
- https://git.kernel.org/stable/c/45a93111835ccfea7d969ec73588e33745fd9834
- https://git.kernel.org/stable/c/f96e91748f6304668fe647e686d199d7207d36f1
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Sources
- CVE-2026-98794 · CVE Program
- CVE-2026-98794 · NVD
- FIRST EPSS
- GHSA-c8w6-8f9f-2m9q · GitHub Advisory Database · CC BY 4.0
- CVE-2026-98794 · 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