CVE-2026-98794

ipvs: filter some flags received in the backup server

State: Published
Severity: Not scored
Published: Oct 18, 2026
Updated: Oct 30, 2026
Reserved: Sep 25, 2026

Description

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.

Scores

The record has no CVSS score.

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	87375ab47cd0ba04124c6d3fd80db5c368f5dcb6 to before ef3cd6c0b826e50dc21653b32552e258de6fd51cAffected 87375ab47cd0ba04124c6d3fd80db5c368f5dcb6 to before 3a9f5459db60311643bfbadf019f6d5370f2f26aAffected 87375ab47cd0ba04124c6d3fd80db5c368f5dcb6 to before 438a5335276614186d6a96b8e7bddce811ad4ad6Affected 87375ab47cd0ba04124c6d3fd80db5c368f5dcb6 to before d7d33c9efa9d1a2f244a1a64ec9b540b0f8975a0Affected 87375ab47cd0ba04124c6d3fd80db5c368f5dcb6 to before f4cd1db7d421e82945713a36084bb0c35b75b27eAffected 87375ab47cd0ba04124c6d3fd80db5c368f5dcb6 to before 55d033324f67a15ff56be6d38d6e87f644e0ed62Affected 87375ab47cd0ba04124c6d3fd80db5c368f5dcb6 to before 45a93111835ccfea7d969ec73588e33745fd9834Affected 87375ab47cd0ba04124c6d3fd80db5c368f5dcb6 to before f96e91748f6304668fe647e686d199d7207d36f1Affected
LinuxLinux	2.6.14Affected before 2.6.14Not affected 5.10.273 through 5.10.Not affected 5.15.224 through 5.15.Not affected 6.1.191 through 6.1.Not affected 6.6.160 through 6.6.Not affected 6.12.113 through 6.12.Not affected 6.18.56 through 6.18.Not affected 7.2.10 through 7.2.*Not affected 7.3 and laterNot affected

Product

Versions

LinuxLinux

87375ab47cd0ba04124c6d3fd80db5c368f5dcb6 to before ef3cd6c0b826e50dc21653b32552e258de6fd51cAffected
87375ab47cd0ba04124c6d3fd80db5c368f5dcb6 to before 3a9f5459db60311643bfbadf019f6d5370f2f26aAffected
87375ab47cd0ba04124c6d3fd80db5c368f5dcb6 to before 438a5335276614186d6a96b8e7bddce811ad4ad6Affected
87375ab47cd0ba04124c6d3fd80db5c368f5dcb6 to before d7d33c9efa9d1a2f244a1a64ec9b540b0f8975a0Affected
87375ab47cd0ba04124c6d3fd80db5c368f5dcb6 to before f4cd1db7d421e82945713a36084bb0c35b75b27eAffected
87375ab47cd0ba04124c6d3fd80db5c368f5dcb6 to before 55d033324f67a15ff56be6d38d6e87f644e0ed62Affected
87375ab47cd0ba04124c6d3fd80db5c368f5dcb6 to before 45a93111835ccfea7d969ec73588e33745fd9834Affected
87375ab47cd0ba04124c6d3fd80db5c368f5dcb6 to before f96e91748f6304668fe647e686d199d7207d36f1Affected

LinuxLinux

2.6.14Affected
before 2.6.14Not affected
5.10.273 through 5.10.*Not affected
5.15.224 through 5.15.*Not affected
6.1.191 through 6.1.*Not affected
6.6.160 through 6.6.*Not affected
6.12.113 through 6.12.*Not affected
6.18.56 through 6.18.*Not affected
7.2.10 through 7.2.*Not affected
7.3 and laterNot affected

References

Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.