CVE-2026-53366 ipv4: account for fraggap on the paged allocation path

What is CVE-2026-53366?

CVE-2026-53366 is a high-severity vulnerability in Linux kernel, published on 16 Jul 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:

ipv4: account for fraggap on the paged allocation path

In __ip_append_data(), when the paged-allocation branch is taken, alloclen and pagedlen are computed as

alloclen = fragheaderlen + transhdrlen; pagedlen = datalen - transhdrlen;

datalen already includes fraggap, but the fraggap bytes carried over from the previous skb are copied into the new skb's linear area at offset transhdrlen by the subsequent skb_copy_and_csum_bits(). The linear area is therefore undersized by fraggap bytes while pagedlen is overstated by the same amount.

The non-paged branch sets alloclen to fraglen, which already accounts for fraggap because datalen does. Bring the paged branch in line by adding fraggap to alloclen and subtracting it from pagedlen.

After this adjustment, copy no longer collapses to -fraggap on the paged path, so remove the stale comment describing that old arithmetic.

Weakness: CWE-131

Which versions are affected by CVE-2026-53366?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-53366?

Apply the vendor's patch.

Is CVE-2026-53366 being exploited?

There is no known exploitation of CVE-2026-53366 in the wild and no public exploit code.

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 BELL-CVE-2026-53366, DEBIAN-CVE-2026-53366, GHSA-r67c-r6r6-mj6m, ROOT-OS-DEBIAN-12-CVE-2026-53366, ROOT-OS-UBUNTU-2404-CVE-2026-53366, SUSE-SU-2026:3253-1 and 2 more.