VulnerabilityPublished 7 Nov 2026

CVE-2026-99283: Linux kernel · netfilter: conntrack: tcp: use UNACK timeout for non-closing RST packets

Source GCVE Database

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Authoritative record:CVE-2026-99283· Medium

Not known to be exploited · fixed in bf80e6802273a900311b44e47c9b1a59c6d2473c : update Linux kernel when convenient.

Data as of 7 Nov 2026, 22:49 UTC

Severity

Medium

Rated Medium by Threat Radar's AI analysis · CVSS not yet scored by NVD

Thin evidence

One scorer or none

Patch: Available – fixed in bf80e6802273a900311b44e47c9b1a59c6d2473c, 6.18.61, 0c6d33329960b2d884a399196c8403643d8a9de6

Exploitation evidence

Disclosed: evidence found.
CVE published 7 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 7 Nov 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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), 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.

ghsa-cr3v-f62w-cwx5

What to do

Upgrade Linux to bf80e6802273a900311b44e47c9b1a59c6d2473c, 6.18.61 or 0c6d33329960b2d884a399196c8403643d8a9de6; the Red Hat redhat/kernel package to 6.18.61.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected <6.18.61	Fixed in bf80e6802273a900311b44e47c9b1a59c6d2473c 6.18.61 0c6d33329960b2d884a399196c8403643d8a9de6
Red Hatredhat/kernel`pkg:rpm/redhat/kernel`Other threats	Affected <6.18.61	Fixed in 6.18.61

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix has been implemented in the Linux kernel to use the UNACK timeout for non-closing RST packets that keep the connection established. Users should apply the official kernel update containing this patch to ensure correct timeout handling in conntrack. No additional mitigation is required beyond applying the fix.

Description

A vulnerability in the Linux kernel's netfilter conntrack TCP handling was addressed by changing the timeout used for certain non-closing RST packets. Previously, the timeout was incorrectly set to a short close timeout even when the connection remained established, potentially allowing conntrack entries to expire prematurely while TCP endpoints were still active. The fix uses the UNACK timeout for these RST packets, avoiding premature expiration while preserving appropriate timeouts for closing RSTs.

Impact

The vulnerability could cause premature expiration of conntrack entries for established TCP connections when non-exact RST packets are received. This may lead to stale or dropped connection tracking state, potentially disrupting network traffic or firewall stateful filtering relying on conntrack. However, the endpoints themselves remain established, so the impact is limited to connection tracking state consistency.

References

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