VulnerabilityPublished 18 Oct 2026Updated 21 Oct 2026

CVE-2026-98794: Linux kernel · ipvs: filter some flags received in the backup server

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in f96e91748f6304668fe647e686d199d7207d36f1 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 13:47 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.2% chance of exploitation in 30 days – higher than 9% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in f96e91748f6304668fe647e686d199d7207d36f1, f4cd1db7d421e82945713a36084bb0c35b75b27e, d7d33c9efa9d1a2f244a1a64ec9b540b0f8975a0 +2

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 87375ab47cd0ba04124c6d3fd80db5c368f5dcb6, < f96e91748f6304668fe647e686d199d7207d36f1	Fixed in f96e91748f6304668fe647e686d199d7207d36f1
LinuxLinux	Affected ≥ 87375ab47cd0ba04124c6d3fd80db5c368f5dcb6, < f4cd1db7d421e82945713a36084bb0c35b75b27e	Fixed in f4cd1db7d421e82945713a36084bb0c35b75b27e
LinuxLinux	Affected ≥ 87375ab47cd0ba04124c6d3fd80db5c368f5dcb6, < d7d33c9efa9d1a2f244a1a64ec9b540b0f8975a0	Fixed in d7d33c9efa9d1a2f244a1a64ec9b540b0f8975a0
LinuxLinux	Affected ≥ 87375ab47cd0ba04124c6d3fd80db5c368f5dcb6, < 55d033324f67a15ff56be6d38d6e87f644e0ed62	Fixed in 55d033324f67a15ff56be6d38d6e87f644e0ed62
LinuxLinux	Affected ≥ 87375ab47cd0ba04124c6d3fd80db5c368f5dcb6, < 45a93111835ccfea7d969ec73588e33745fd9834	Fixed in 45a93111835ccfea7d969ec73588e33745fd9834
LinuxLinux	Affected =2.6.14	Fixed in–

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.

References

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