CVE-2026-46300: Linux Kernel Missing Initialization of a Variable Vulnerability

Reference page built from the source records below, each shown as its source publishes it. Dataset version ref-f67404b7ab4b, updated 2026-11-02T23:39:54.475Z.

CISA Known Exploited Vulnerabilities

Name
Linux Kernel Missing Initialization of a Variable Vulnerability
Vendor
Linux
Product
Kernel
Added to the catalog
2026-10-28
Due date for US federal agencies
2026-10-31
Weaknesses
CWE-456
Catalog version
2026.10.30

Linux Kernel contains a missing initialization of a variable vulnerability that could allow for unintended modification of page-cache-backed data via failure to preserve the shared-fragment marker during socket buffer coalescing, causing ESP input processing to decrypt shared fragments in place. This vulnerability can be chained with CVE-2026-109618 and CVE-2026-109619 to implant PHP webshells and run commands as root.

Required action (CISA)

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

Ransomware use: CISA does not mark known use of this vulnerability in ransomware campaigns.

Links in CISA's notes

Read on 2026-11-02T23:39:54.475Z under licence cisa-kev-cc0@b0067899 from https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json

NVD analysis

Status
Analyzed
Published
2026-05-23T12:17:02.660
Last modified
2026-10-29T17:30:34.060
Weaknesses
CWE-787, CWE-456, CWE-123

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

net: skbuff: preserve shared-frag marker during coalescing

skb_try_coalesce() can attach paged frags from @from to @to. If @from
has SKBFL_SHARED_FRAG set, the resulting @to skb can contain the same
externally-owned or page-cache-backed frags, but the shared-frag marker
is currently lost.

That breaks the invariant relied on by later in-place writers. In
particular, ESP input checks skb_has_shared_frag() before deciding
whether an uncloned nonlinear skb can skip skb_cow_data(). If TCP
receive coalescing has moved shared frags into an unmarked skb, ESP can
see skb_has_shared_frag() as false and decrypt in place over page-cache
backed frags.

Propagate SKBFL_SHARED_FRAG when skb_try_coalesce() transfers paged
frags. The tailroom copy path does not need the marker because it copies
bytes into @to's linear data rather than transferring frag descriptors.

MetricScoreSeverityVectorScored by
CVSS 3.17.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Secondary)
CVSS 3.17.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H[email protected] (Primary)
CVSS 3.17.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H0b0ca135-0b70-47e7-9f44-1890c2a1c46c (Secondary)

References

This product uses the NVD API but is not endorsed or certified by the NVD.

Read on 2026-11-02T23:42:31.494Z under licence nvd-api-terms-of-use@ff2a5288 from https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-46300

CVE record

Title (CNA)
net: skbuff: preserve shared-frag marker during coalescing
Assigner
Linux
State
PUBLISHED
Published
2026-05-23T11:44:02.231Z
Updated
2026-10-29T03:55:37.330Z

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

net: skbuff: preserve shared-frag marker during coalescing

skb_try_coalesce() can attach paged frags from @from to @to. If @from
has SKBFL_SHARED_FRAG set, the resulting @to skb can contain the same
externally-owned or page-cache-backed frags, but the shared-frag marker
is currently lost.

That breaks the invariant relied on by later in-place writers. In
particular, ESP input checks skb_has_shared_frag() before deciding
whether an uncloned nonlinear skb can skip skb_cow_data(). If TCP
receive coalescing has moved shared frags into an unmarked skb, ESP can
see skb_has_shared_frag() as false and decrypt in place over page-cache
backed frags.

Propagate SKBFL_SHARED_FRAG when skb_try_coalesce() transfers paged
frags. The tailroom copy path does not need the marker because it copies
bytes into @to's linear data rather than transferring frag descriptors.

References

Read on 2026-11-03T02:20:13.608Z under licence cve-terms-of-use@81bfa2f3 from https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/46xxx/CVE-2026-46300.json

Defensive techniques (MITRE D3FEND)

D3FEND maps these defensive techniques to the weakness (CWE) that NVD lists for this CVE, through the digital artifacts the weakness affects. D3FEND does not say they stop this vulnerability.

CWE-123: Write-what-where Condition

D3FEND ontology version 1.6.0.

Read on 2026-11-02T23:54:45.293Z under licence d3fend-terms-of-use@f98cbc7e from https://d3fend.mitre.org/api/weakness/cwe/CWE-123.json

CWE-787: Out-of-bounds Write

D3FEND ontology version 1.6.0.

Read on 2026-11-03T00:02:57.820Z under licence d3fend-terms-of-use@f98cbc7e from https://d3fend.mitre.org/api/weakness/cwe/CWE-787.json

MITRE D3FEND™ knowledge graph. © 2025 The MITRE Corporation.
"The MITRE Corporation (MITRE) hereby grants you a non-exclusive, royalty-free license to use D3FEND for research, development, and commercial purposes. Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." Terms: https://d3fend.mitre.org/tou/

Sources and licences

  • CISA

    Source: CISA Catalog of Known Exploited Vulnerabilities, version 2026.10.30, CC0 1.0. Use of this data does not imply endorsement by CISA or DHS.

    CC0 1.0 Universal

  • National Vulnerability Database (NIST)

    This product uses the NVD API but is not endorsed or certified by the NVD.

    NVD API Terms of Use (NIST publications in the public domain, 17 U.S.C. 105)

  • CVE Program, The MITRE Corporation

    Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation. CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy.

    CVE Program Terms of Use ("CVE Usage" licence)

  • MITRE D3FEND

    MITRE D3FEND™ knowledge graph. © 2025 The MITRE Corporation.
    "The MITRE Corporation (MITRE) hereby grants you a non-exclusive, royalty-free license to use D3FEND for research, development, and commercial purposes. Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." Terms: https://d3fend.mitre.org/tou/

    MITRE D3FEND Terms of Use (site + knowledge graph); source repo MIT

Cite this page

Dragons Eye Ransomware Tracker, "CVE-2026-46300: Linux Kernel Missing Initialization of a Variable Vulnerability",
entity page, dataset version ref-f67404b7ab4b, updated 2026-11-02T23:39:54.475Z,
https://ransomware-tracker.com/cve/CVE-2026-46300 (accessed 2026-11-03).
Underlying source: CISA Catalog of Known Exploited Vulnerabilities, version 2026.10.30.
Underlying source: National Vulnerability Database (NIST), CVE API 2.0, record last modified 2026-10-29T17:30:34.060.
Underlying source: CVE List (CVE Program, The MITRE Corporation), record updated 2026-10-29T03:55:37.330Z.
Underlying source: MITRE D3FEND, ontology version 1.6.0.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.

CISA KEV index