VulnerabilityPublished 23 Oct 2026

CVE-2026-98873: Linux kernel · netfilter: nf_conntrack_expect: zero at allocation time

Source GCVE Database

Authoritative record:CVE-2026-98873· Medium

Not known to be exploited · fixed in b7f3ee925aee9f1f547d539bc03c35433c238958 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 12:55 UTC

Severity

Medium

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in b7f3ee925aee9f1f547d539bc03c35433c238958, a39ecb856514274c80d0fac4d128dba6b266a8ed, 824397af7bfe14edad374c64253dae0187ca623d +4

Exploitation evidence

Disclosed: evidence found.
CVE published 23 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-9v8r-rm7r-2xx4

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 076a0ca02644657b13e4af363f487ced2942e9cb, < b7f3ee925aee9f1f547d539bc03c35433c238958	Fixed in b7f3ee925aee9f1f547d539bc03c35433c238958
LinuxLinux	Affected ≥ 076a0ca02644657b13e4af363f487ced2942e9cb, < a39ecb856514274c80d0fac4d128dba6b266a8ed	Fixed in a39ecb856514274c80d0fac4d128dba6b266a8ed
LinuxLinux	Affected ≥ 076a0ca02644657b13e4af363f487ced2942e9cb, < 824397af7bfe14edad374c64253dae0187ca623d	Fixed in 824397af7bfe14edad374c64253dae0187ca623d
LinuxLinux	Affected ≥ 076a0ca02644657b13e4af363f487ced2942e9cb, < 90545aa07a183887e9d72ce573c18e08f62e2c91	Fixed in 90545aa07a183887e9d72ce573c18e08f62e2c91
LinuxLinux	Affected ≥ 076a0ca02644657b13e4af363f487ced2942e9cb, < 241ccd2fed9051db443aadce248fc0ab30f55e97	Fixed in 241ccd2fed9051db443aadce248fc0ab30f55e97
LinuxLinux	Affected ≥ 076a0ca02644657b13e4af363f487ced2942e9cb, < 39cb6ff947c16a576ea68c5f272e634acdcb0085	Fixed in 39cb6ff947c16a576ea68c5f272e634acdcb0085

AI-suggested

A fix has been applied to the Linux kernel to zero the nf_conntrack_expect structure at allocation time, preventing uninitialized data leakage. Users should update to the patched kernel version once available. No additional mitigation is indicated by the vendor advisory.

Description

A vulnerability in the Linux kernel's netfilter subsystem related to nf_conntrack_expect was resolved. The issue involved occasional leaking of uninitialized data to userspace via ctnetlink due to missing zeroing at allocation time. The fix involved zeroing the expectation structure at allocation to prevent data leakage. This vulnerability affects the kernel's connection tracking expectations, which are infrequently used. No CVSS score is available for this issue.

Impact

The vulnerability could lead to leakage of uninitialized kernel memory to userspace, potentially exposing sensitive kernel data. However, the affected structure (expectations) is not frequently used, which may limit the exposure. There are no known exploits in the wild. The impact is primarily information disclosure through uninitialized memory leakage.

Summary

The Linux kernel netfilter component had a vulnerability (CVE-2026-98873) where the nf_conntrack_expect structure was not zeroed at allocation time, leading to occasional leakage of uninitialized kernel memory to userspace through the ctnetlink interface. The vulnerability was addressed by zeroing the expectation structure upon allocation, preventing uninitialized data exposure. The fix also preserved the existing initialization behavior to allow potential re-initialization support.

References

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