CVE-2026-46300
net: skbuff: preserve shared-frag marker during coalescing
Linux Kernel Missing Initialization of a Variable Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.
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.
CISA 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
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.
Severity
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HKey Findings
as of 2026-11-01- CISA added CVE-2026-46300 to the KEV catalog 158 days after its CVE record was published. The median for entries added in 2026 so far is 14 days.
- It is one of 32 Linux Kernel entries in the CISA KEV catalog, and one of 9 added in 2026.
- Its current EPSS score (16.1%) is higher than that of 30% of CISA KEV entries.
Affected Products
| Vendor | Product | Affected versions |
|---|---|---|
| Linux | Linux Linux | cef401de7be8c4e155c6746bfccf721a4fa5fab9 to <3599e6b3cc1ada96883d496a50a210d3afbb6987 cef401de7be8c4e155c6746bfccf721a4fa5fab9 to <2f2b16022a2e10ca7bccfb98db5ed2ec0f72641c cef401de7be8c4e155c6746bfccf721a4fa5fab9 to <9d3e5fd19fe1063bf607219e8562fbd567b8e8d5 cef401de7be8c4e155c6746bfccf721a4fa5fab9 to <78bf6b6bb19541d19fbda6242e7cfe2c682763c0 cef401de7be8c4e155c6746bfccf721a4fa5fab9 to <760e1addc27ba1a7beb4a0a7e8b3e9ec49e7a34e cef401de7be8c4e155c6746bfccf721a4fa5fab9 to <3bd9e113d50034db99d7ef69fd8e5242d15e414a cef401de7be8c4e155c6746bfccf721a4fa5fab9 to <3884358a9286b17f389a72b1426fc4547c23c111 cef401de7be8c4e155c6746bfccf721a4fa5fab9 to <f84eca5817390257cef78013d0112481c503b4a3 |
| Linux | Linux Linux | 3.9 0 to <3.9 (unaffected) 5.10.257 to 5.10.* (unaffected) 5.15.208 to 5.15.* (unaffected) 6.1.174 to 6.1.* (unaffected) 6.6.141 to 6.6.* (unaffected) 6.12.91 to 6.12.* (unaffected) 6.18.33 to 6.18.* (unaffected) 7.0.10 to 7.0.* (unaffected) 7.1 to * (unaffected) |
References
12 linksOther references
- 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
- http://www.openwall.com/lists/oss-security/2026/05/13/5
- http://www.openwall.com/lists/oss-security/2026/05/21/11
- http://www.openwall.com/lists/oss-security/2026/05/21/12
- http://www.openwall.com/lists/oss-security/2026/05/21/13
Record Details
- Published
- 2026-05-23
- Last updated
- 2026-10-29
- Assigner (CNA)
- Linux
- Credited to
- -
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