CVE-2026-46300
net: skbuff: preserve shared-frag marker during coalescing
What happened?
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 software and versions
| Software | Version information | Fixed version |
|---|---|---|
| LinuxLinux | affected: cef401de7be8c4e155c6746bfccf721a4fa5fab9 to < 3599e6b3cc1ada96883d496a50a210d3afbb6987; affected: cef401de7be8c4e155c6746bfccf721a4fa5fab9 to < 2f2b16022a2e10ca7bccfb98db5ed2ec0f72641c; affected: cef401de7be8c4e155c6746bfccf721a4fa5fab9 to < 9d3e5fd19fe1063bf607219e8562fbd567b8e8d5; affected: cef401de7be8c4e155c6746bfccf721a4fa5fab9 to < 78bf6b6bb19541d19fbda6242e7cfe2c682763c0; affected: cef401de7be8c4e155c6746bfccf721a4fa5fab9 to < 760e1addc27ba1a7beb4a0a7e8b3e9ec49e7a34e; affected: cef401de7be8c4e155c6746bfccf721a4fa5fab9 to < 3bd9e113d50034db99d7ef69fd8e5242d15e414a; affected: cef401de7be8c4e155c6746bfccf721a4fa5fab9 to < 3884358a9286b17f389a72b1426fc4547c23c111; affected: cef401de7be8c4e155c6746bfccf721a4fa5fab9 to < f84eca5817390257cef78013d0112481c503b4a3 | See vendor advisory |
| LinuxLinux | affected: 3.9; unaffected: 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 ≤ * | See vendor advisory |
Version information comes from the source record and can include unaffected products and exceptions. Distribution packages may contain backported fixes: an older upstream version alone does not prove a server is affected.
Is it being exploited?
CISA lists this CVE in its Known Exploited Vulnerabilities catalogue. Added 2026-10-28.
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.
How to respond
- Confirm the product, installed package version, and any configuration requirements in the vendor advisory.
- Follow the vendor’s remediation or workaround guidance in the references below. Structured fixed-version data is unavailable here; the publisher’s description may include a fix or workaround.
- Restart affected services if required, then verify the running version. Known exploitation may warrant investigation as well as patching.
Sources and remediation references
- https://www.cve.org/CVERecord?id=CVE-2026-46300
- 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
- https://access.redhat.com/security/cve/CVE-2026-46300
- https://bugzilla.redhat.com/show_bug.cgi?id=2477015
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-46300.json
- https://access.redhat.com/errata/RHSA-2026:19540
- https://access.redhat.com/errata/RHSA-2026:33486
- https://access.redhat.com/errata/RHBA-2026:20032
- https://access.redhat.com/errata/RHSA-2026:21695
- https://access.redhat.com/errata/RHSA-2026:21690
- https://access.redhat.com/errata/RHSA-2026:28887
- https://access.redhat.com/errata/RHSA-2026:23233
- https://access.redhat.com/errata/RHSA-2026:20087
- https://access.redhat.com/errata/RHSA-2026:25044
- https://access.redhat.com/errata/RHSA-2026:34098
- https://access.redhat.com/errata/RHSA-2026:21656
- https://access.redhat.com/errata/RHSA-2026:23245
- https://access.redhat.com/errata/RHSA-2026:21702
- https://access.redhat.com/errata/RHSA-2026:23240