VulnerabilityPublished 18 Oct 2026Updated 21 Oct 2026

CVE-2026-98793: Linux kernel · netfilter: bpf: reject invalid NAT manipulation types

Source GCVE Database

Authoritative record:CVE-2026-98793

Not known to be exploited · fixed in f6143ae109df56d51d5536e813deb19eee7a6205 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 13:47 UTC

Severity

Medium

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in f6143ae109df56d51d5536e813deb19eee7a6205, ea777dc90ab37e64fa4b92f6fcf3b5edcef5e058, 752492947be3123ea6c689e2f93ae04ecd675d42 +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.

ghsa-g33v-6845-q9px

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 0fabd2aa199faeb8754aee94658f2c48ccb2c8c3, < f6143ae109df56d51d5536e813deb19eee7a6205	Fixed in f6143ae109df56d51d5536e813deb19eee7a6205
LinuxLinux	Affected ≥ 0fabd2aa199faeb8754aee94658f2c48ccb2c8c3, < ea777dc90ab37e64fa4b92f6fcf3b5edcef5e058	Fixed in ea777dc90ab37e64fa4b92f6fcf3b5edcef5e058
LinuxLinux	Affected ≥ 0fabd2aa199faeb8754aee94658f2c48ccb2c8c3, < 752492947be3123ea6c689e2f93ae04ecd675d42	Fixed in 752492947be3123ea6c689e2f93ae04ecd675d42
LinuxLinux	Affected ≥ 0fabd2aa199faeb8754aee94658f2c48ccb2c8c3, < 58108f05b0502448f6bb612ee2eccc63bd6449cb	Fixed in 58108f05b0502448f6bb612ee2eccc63bd6449cb
LinuxLinux	Affected ≥ 0fabd2aa199faeb8754aee94658f2c48ccb2c8c3, < 16d464013ec2267b00a83f4bfbb97b3ecc63bfa7	Fixed in 16d464013ec2267b00a83f4bfbb97b3ecc63bfa7
LinuxLinux	Affected =6.1	Fixed in–

AI-suggested

A fix has been implemented in the Linux kernel to validate NAT manipulation types before processing and to drop packets when invalid types are detected. Users should apply the official kernel updates that include this patch. Since this is a kernel-level fix, upgrading to the patched kernel version is the recommended mitigation.

Description

A vulnerability in the Linux kernel's netfilter subsystem related to BPF NAT manipulation types has been resolved. The function bpf_ct_set_nat_info() did not validate the NAT manipulation type, allowing invalid values to be passed to nf_nat_setup_info(). This caused a WARN_ON() trigger and potential improper connection tracking cleanup. The fix involves validating the NAT manipulation type before processing and dropping packets if invalid types are detected.

Impact

This vulnerability could cause kernel warnings and potentially unstable connection tracking behavior due to improper cleanup of uninitialized data structures. While it does not explicitly state remote code execution or privilege escalation, the improper handling could lead to kernel instability or denial of service conditions under certain circumstances.

Summary

The Linux kernel vulnerability (CVE-2026-98793) involves improper validation in the netfilter BPF component. Specifically, bpf_ct_set_nat_info() failed to verify the NAT manipulation type before passing it to nf_nat_setup_info(), which could lead to a WARN_ON() condition. If panic_on_warn is not enabled, this results in setting IPS_SRC_NAT_DONE without properly adding nat_bysource, causing conntrack cleanup to attempt unlinking an uninitialized hlist node. The patch adds validation of the NAT manipulation type and changes the behavior to return NF_DROP if WARN_ON() is triggered, preventing further processing and similar issues.

References

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