CVEvulnerability

CVE-2026-46300

7.8 HIGH Known exploited Published 2026-05-23 Modified 2026-10-29 Official page ↗

CISA Known Exploited Vulnerability

Linux Kernel Missing Initialization of a Variable Vulnerability — Linux Kernel

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.

Added to KEV
2026-10-28
Remediation due
2026-10-31
Ransomware use
Unknown
Required action
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.
Notes
This vulnerability affects an open-source component, third-party library, protocol, or proprietary implementation that could be used by different products. For more information, please see: ; https://git.kernel.org/stable/c/3599e6b3cc1ada96883d496a50a210d3afbb6987 ; https://git.kernel.org/stable/c/2f2b16022a2e10ca7bccfb98db5ed2ec0f72641c ; https://git.kernel.org/stable/c/9d3e5fd19fe1063bf607219e8562fbd567b8e8d5 ; https://git.kernel.org/stable/c/78bf6b6bb19541d19fbda6242e7cfe2c682763c0 ; https://git.kernel.org/stable/c/760e1addc27ba1a7beb4a0a7e8b3e9ec49e7a34e ; https://git.kernel.org/stable/c/3bd9e113d50034db99d7ef69fd8e5242d15e414a ; https://git.kernel.org/stable/c/3884358a9286b17f389a72b1426fc4547c23c111 ; https://git.kernel.org/stable/c/f84eca5817390257cef78013d0112481c503b4a3 ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-46300
Status
Analyzed
Published
2026-05-23
Last modified
2026-10-29
Assigner
416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS 3.1 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)
7.8 HIGH — CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS 3.1 ([email protected])
7.8 HIGH — CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS 3.1 (0b0ca135-0b70-47e7-9f44-1890c2a1c46c)
7.8 HIGH — CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weaknesses
CWE-123, CWE-456, CWE-787

Description

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.

Affected configurations

• linux linux kernel (>= 3.9 <= 5.10.257) • linux linux kernel (>= 5.11 < 5.15.208) • linux linux kernel (>= 5.16 < 6.1.174) • linux linux kernel (>= 6.2 < 6.6.141) • linux linux kernel (>= 6.7 < 6.12.91) • linux linux kernel (>= 6.13 < 6.18.33) • linux linux kernel (>= 6.19 < 7.0.10) • linux linux kernel 7.1 • siemens simatic s7-1500 cpu 1518-4 pn\/dp mfp firmware (>= 3.1.5 <= 3.1.6) • redhat openshift container platform (>= 4.12 < 4.12.91) • redhat openshift container platform (>= 4.13 < 4.13.67) • redhat openshift container platform (>= 4.14 < 4.14.68) • redhat openshift container platform (>= 4.15 < 4.15.65) • redhat openshift container platform (>= 4.16 < 4.16.63) • redhat openshift container platform (>= 4.17 < 4.17.55) • redhat openshift container platform (>= 4.18 < 4.18.43) • redhat openshift container platform (>= 4.19 < 4.19.33) • redhat openshift container platform (>= 4.20 < 4.20.24) • redhat openshift container platform (>= 4.21 < 4.21.17) • redhat enterprise linux 6.0 • redhat enterprise linux 7.0 • redhat enterprise linux 8.0 • redhat enterprise linux 9.0 • redhat enterprise linux 10.0 • redhat enterprise linux aus 8.4 • redhat enterprise linux aus 8.6 • redhat enterprise linux eus 8.4 • redhat enterprise linux eus 9.4 • redhat enterprise linux eus 9.6 • redhat enterprise linux eus 10.0 • redhat enterprise linux tus 8.6 • redhat enterprise linux tus 8.8 • redhat enterprise linux update services for sap solutions 8.6 • redhat enterprise linux update services for sap solutions 8.8 • redhat enterprise linux update services for sap solutions 9.0 • redhat enterprise linux update services for sap solutions 9.2 • redhat enterprise linux update services for sap solutions 9.4

Related

Weakness · CWE (3)

  • CWE-123 Write-what-where Condition weakness
  • CWE-456 Missing Initialization of a Variable weakness
  • CWE-787 Out-of-bounds Write weakness

References