All vulnerabilities
CVE-2026-98794

Linux: ipvs: filter some flags received in the backup server

Linux LinuxOperating systems
Open in ThreatlineRecord JSON
CVSS
NoneNot scored
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.20%Chance of exploitation activity in the next 30 days, higher than 9% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in55d033324f67a15ff56be6d38d6e87f644e0ed62Also 45a93111835ccfea7d969ec73588e33745fd9834CVE List
Published18 Oct 2026Updated 21 Oct 2026CVE List

What fixes it

  • 55d033324f67a15ff56be6d38d6e87f644e0ed62LinuxCVE List
  • 45a93111835ccfea7d969ec73588e33745fd9834LinuxCVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

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.

  1. 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.

Text from CVE List

Affected versions 12

  • Linuxaffected: 87375ab47cd0ba04124c6d3fd80db5c368f5dcb6 before d7d33c9efa9d1a2f244a1a64ec9b540b0f8975a0CVE List
  • Linuxaffected: 87375ab47cd0ba04124c6d3fd80db5c368f5dcb6 before f4cd1db7d421e82945713a36084bb0c35b75b27eCVE List
  • Linuxaffected: 87375ab47cd0ba04124c6d3fd80db5c368f5dcb6 before 55d033324f67a15ff56be6d38d6e87f644e0ed62CVE List
  • Linuxaffected: 87375ab47cd0ba04124c6d3fd80db5c368f5dcb6 before 45a93111835ccfea7d969ec73588e33745fd9834CVE List
  • Linuxaffected: 87375ab47cd0ba04124c6d3fd80db5c368f5dcb6 before f96e91748f6304668fe647e686d199d7207d36f1CVE List
  • Linuxaffected: 2.6.14CVE List
  • Linuxunaffected: all versions before 2.6.14CVE List
  • Linuxunaffected: 6.6.160 through 6.6.*CVE List
  • Linuxunaffected: 6.12.113 through 6.12.*CVE List
  • Linuxunaffected: 6.18.56 through 6.18.*CVE List
  • Linuxunaffected: 7.2.10 through 7.2.*CVE List
  • Linuxunaffected: 7.3CVE List

References 5