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

What is CVE-2026-46300?

CVE-2026-46300 is a high-severity memory corruption vulnerability in Linux kernel, published on 23 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official 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.

Weakness: CWE-787, CWE-123, CWE-456

Which versions are affected by CVE-2026-46300?

It affects 8 products.

Products include Linux kernel, Redhat Enterprise Linux, Redhat Enterprise Linux Aus, Redhat Enterprise Linux Eus, Redhat Enterprise Linux Tus, Redhat Enterprise Linux Update Services for Sap Solutions and 2 more.

How do I fix CVE-2026-46300?

Apply the vendor's patch. US federal agencies must fix it by 31 Oct 2026.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-46300 being exploited?

Yes. Attackers have exploited CVE-2026-46300 in the wild since at least 28 Oct 2026.

Public exploit code: 1 Metasploit module, 1 Exploit-DB entry and 15 proofs of concept on GitHub.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-87351, BELL-CVE-2026-46300, CLSA-2026-1778783204, CLSA-2026-1778783464, CLSA-2026-1778832730, CLSA-2026-1778832754 and 11 more.