CVE-2026-98873 - Vulnerability Details

- netfilter: nf_conntrack_expect: zero at allocation time

Description

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nf_conntrack_expect: zero at allocation time

There are occasional LLM hints wrt. leaking uninitialized data to
userspace via ctnetlink. Just zero at allocation time,
expectations are not frequently used these days.

Intentionally keeps _init as-is because we could theoretically
support re-init, so add the missing exp->dir there.

Published: 2026-10-23

Score: 3.3 Low

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

A flaw in the nf_conntrack_expect subsystem leads to partial uninitialization of the memory allocated for expectation structures. When these structures are exposed to userspace through the ct netlink interface, stale kernel data may be returned to the caller. This stems from the weakness type CWE-908.

Affected Systems

All Linux kernel releases that employ the nf_conntrack_expect feature and have not incorporated the specified patch. The vulnerability exists in the netfilter component of the upstream kernel and applies to any distribution shipping that code prior to the reference commit.

Risk and Exploitability

The CVSS score is 3.3, and the EPSS score is less than 1%, indicating a low probability of exploitation. The flaw is likely exploitable only from user space through the ct netlink interface, which typically requires local access. Based on the description, it is inferred that exploitation requires local execution; therefore the threat is limited to compromised or privileged users who can issue netlink commands. Because many deployments allow non‑privileged users access to ct netlink, the risk of data exposure is realistic, but the scope is confined to local processes. The vulnerability is not documented in the CISA KEV catalog.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Linux

unaffected

Version	Status	Constraints
`076a0ca02644657b13e4af363f487ced2942e9cb`	affected	< 39cb6ff947c16a576ea68c5f272e634acdcb0085
`076a0ca02644657b13e4af363f487ced2942e9cb`	affected	< 90545aa07a183887e9d72ce573c18e08f62e2c91
`076a0ca02644657b13e4af363f487ced2942e9cb`	affected	< 9c11d7ea5ff4dbe162e79f00188814ef5483c295
`076a0ca02644657b13e4af363f487ced2942e9cb`	affected	< b7f3ee925aee9f1f547d539bc03c35433c238958
`076a0ca02644657b13e4af363f487ced2942e9cb`	affected	< 824397af7bfe14edad374c64253dae0187ca623d
`076a0ca02644657b13e4af363f487ced2942e9cb`	affected	< a39ecb856514274c80d0fac4d128dba6b266a8ed
`076a0ca02644657b13e4af363f487ced2942e9cb`	affected	< 241ccd2fed9051db443aadce248fc0ab30f55e97

Linux

affected

Version	Status	Constraints
`3.4`	affected	—
`0`	unaffected	< 3.4
`5.10.271`	unaffected	≤ 5.10.*
`5.15.222`	unaffected	≤ 5.15.*
`6.1.189`	unaffected	≤ 6.1.*
`6.6.158`	unaffected	≤ 6.6.*
`6.12.111`	unaffected	≤ 6.12.*
`6.18.53`	unaffected	≤ 6.18.*
`7.2`	unaffected	≤ *

No data.

Vendor Product Confidence Versions

Linux

100%

Version	Status	Scheme	Platform
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,39cb6ff947c16a576ea68c5f272e634acdcb0085)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,90545aa07a183887e9d72ce573c18e08f62e2c91)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,9c11d7ea5ff4dbe162e79f00188814ef5483c295)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,b7f3ee925aee9f1f547d539bc03c35433c238958)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,824397af7bfe14edad374c64253dae0187ca623d)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,a39ecb856514274c80d0fac4d128dba6b266a8ed)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,241ccd2fed9051db443aadce248fc0ab30f55e97)`	affected	code_commit	—
`[0,5.10.271)`	affected	semver	—
`[0,5.15.222)`	affected	semver	—
`[0,6.1.189)`	affected	semver	—
`[0,6.6.158)`	affected	semver	—
`[0,6.12.111)`	affected	semver	—
`[0,6.18.53)`	affected	semver	—

Linux

100%

Version	Status	Scheme	Platform
`[5.10.271,5.11.0)`	unaffected	semver	—
`[5.15.222,5.16.0)`	unaffected	semver	—
`[6.1.189,6.2.0)`	unaffected	semver	—
`[6.6.158,6.7.0)`	unaffected	semver	—
`[6.12.111,6.13.0)`	unaffected	semver	—
`[6.18.53,6.19.0)`	unaffected	semver	—
`[7.2,*]`	unaffected	generic	—

Linux

Linux Kernel

100%

Version	Status	Scheme	Platform
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,39cb6ff947c16a576ea68c5f272e634acdcb0085)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,90545aa07a183887e9d72ce573c18e08f62e2c91)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,9c11d7ea5ff4dbe162e79f00188814ef5483c295)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,b7f3ee925aee9f1f547d539bc03c35433c238958)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,824397af7bfe14edad374c64253dae0187ca623d)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,a39ecb856514274c80d0fac4d128dba6b266a8ed)`	affected	code_commit	—
`[1da177e4c3f41524e886b7f1b8a0c1fc7321cac2,241ccd2fed9051db443aadce248fc0ab30f55e97)`	affected	code_commit	—
`[0,5.10.271)`	affected	semver	—
`[0,5.15.222)`	affected	semver	—
`[0,6.1.189)`	affected	semver	—
`[0,6.6.158)`	affected	semver	—
`[0,6.12.111)`	affected	semver	—
`[0,6.18.53)`	affected	semver	—

Linux

Linux Kernel

100%

Version	Status	Scheme	Platform
`[5.10.271,5.11.0)`	unaffected	semver	—
`[5.15.222,5.16.0)`	unaffected	semver	—
`[6.1.189,6.2.0)`	unaffected	semver	—
`[6.6.158,6.7.0)`	unaffected	semver	—
`[6.12.111,6.13.0)`	unaffected	semver	—
`[6.18.53,6.19.0)`	unaffected	semver	—
`[7.2,*]`	unaffected	generic	—

Found an issue or want to improve our Enrichment? You can suggest it directly by opening an issue on our dedicated GitHub repository .

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Upgrade the Linux kernel to the latest stable release that incorporates the fix for nf_conntrack_expect uninitialization data leakage.
If an immediate kernel update is not possible, ensure that only trusted users have access to ct netlink by tightening SELinux or AppArmor netlink policies and limiting the nf_conntrack_expect module if it is not required for network traffic handling.
Apply the specific kernel commit or patch that zeroes expectation structures at allocation time to eliminate the path that exposes stale data.

Generated by OpenCVE AI on October 26, 2026 at 16:08 UTC.

Tracking

Sign in to view the affected projects.

Advisories

Source	ID	Title
Ubuntu USN	USN-8961-1	Linux kernel vulnerabilities

No CVSS v4.0

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact Low

Integrity Impact None

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00179.

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98873.mbox
https://git.kernel.org/stable/c/241ccd2fed9051db443aadce248fc0ab30f55e97
https://git.kernel.org/stable/c/39cb6ff947c16a576ea68c5f272e634acdcb0085
https://git.kernel.org/stable/c/824397af7bfe14edad374c64253dae0187ca623d
https://git.kernel.org/stable/c/90545aa07a183887e9d72ce573c18e08f62e2c91
https://git.kernel.org/stable/c/9c11d7ea5ff4dbe162e79f00188814ef5483c295
https://git.kernel.org/stable/c/a39ecb856514274c80d0fac4d128dba6b266a8ed
https://git.kernel.org/stable/c/b7f3ee925aee9f1f547d539bc03c35433c238958
https://nvd.nist.gov/vuln/detail/CVE-2026-98873
https://www.cve.org/CVERecord?id=CVE-2026-98873

History

Mon, 26 Oct 2026 14:15:00 +0000

Type	Values Removed	Values Added
Weaknesses	CWE-200 CWE-560

Mon, 26 Oct 2026 12:15:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-908
References		https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98873.mbox https://nvd.nist.gov/vuln/detail/CVE-2026-98873 https://www.cve.org/CVERecord?id=CVE-2026-98873
Metrics	threat_severity `None`	cvssV3_1 `{'score': 3.3, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N'}` threat_severity `Low`

Fri, 23 Oct 2026 18:00:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-200 CWE-560

Fri, 23 Oct 2026 14:15:00 +0000

Type	Values Removed	Values Added
First Time appeared		Linux linux
Vendors & Products		Linux linux

Fri, 23 Oct 2026 12:00:00 +0000

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_expect: zero at allocation time There are occasional LLM hints wrt. leaking uninitialized data to userspace via ctnetlink. Just zero at allocation time, expectations are not frequently used these days. Intentionally keeps _init as-is because we could theoretically support re-init, so add the missing exp->dir there.
Title		netfilter: nf_conntrack_expect: zero at allocation time
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/241ccd2fed9051db443aadce248fc0ab30f55e97 https://git.kernel.org/stable/c/39cb6ff947c16a576ea68c5f272e634acdcb0085 https://git.kernel.org/stable/c/824397af7bfe14edad374c64253dae0187ca623d https://git.kernel.org/stable/c/90545aa07a183887e9d72ce573c18e08f62e2c91 https://git.kernel.org/stable/c/9c11d7ea5ff4dbe162e79f00188814ef5483c295 https://git.kernel.org/stable/c/a39ecb856514274c80d0fac4d128dba6b266a8ed https://git.kernel.org/stable/c/b7f3ee925aee9f1f547d539bc03c35433c238958

Subscriptions

Linux Linux Linux Kernel

MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2026-10-23T11:37:14.109Z

Updated: 2026-10-26T06:55:54.978Z

Reserved: 2026-09-25T10:25:14.377Z

Link: CVE-2026-98873

Vulnrichment

No data.

NVD

Status : Received

Published: 2026-10-23T12:18:20.753

Modified: 2026-10-26T07:17:11.740

Link: CVE-2026-98873

Redhat

Severity : Low

Publid Date: 2026-10-23T00:00:00Z

Links: CVE-2026-98873 - Bugzilla

OpenCVE Enrichment

Updated: 2026-10-26T16:15:14Z

Weaknesses

CWE-908
Use of Uninitialized Resource

Impact

Affected Systems

Risk and Exploitability

Tracking

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact Low

Integrity Impact None

Availability Impact None

User Interaction None

Subscriptions

JSON object

JSON object

JSON object

JSON object

JSON object