--- id: CVE-2026-53366 title: "In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: account for fraggap on the paged allocation path\n\nIn __ip_append_data(), when the paged-allocation branch is taken,\nalloclen and pagedlen are computed as\n\n\tallocl…" summary: "In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: account for fraggap on the paged allocation path\n\nIn __ip_append_data(), when the paged-allocation branch is taken,\nalloclen and pagedlen are computed as\n\n\tallocl…" severity: high cvss: 7.8 cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H' published: '2026-07-16' updated: '2026-07-18' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-53366' references: - url: 'https://git.kernel.org/stable/c/77798d7be6ef71e72fb6fc8a2901bf74ebc9706f' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/a9c24eda24bd15f432e37824e6fc440977cb241c' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/c04d9ece23deb9e26c19f9ca215e98b3295aa1bb' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/ce494707a9c07f27c219ca67f3e138061f53d9b3' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/eca856950f7cb1a221e02b99d758409f2c5cec42' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: >- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-53366.json - url: 'https://access.redhat.com/security/cve/CVE-2026-53366' - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2501252' - url: 'https://www.cve.org/CVERecord?id=CVE-2026-53366' - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-53366' - url: >- https://lore.kernel.org/linux-cve-announce/2026071639-CVE-2026-53366-f508@gregkh/T - url: 'https://access.redhat.com/errata/RHSA-2026:35840' - url: 'https://access.redhat.com/errata/RHSA-2026:34911' - url: 'https://access.redhat.com/errata/RHSA-2026:66180' tags: - nvd - csaf - vex - red-hat epss: 0.00171 epssPercentile: 0.06818 ingestedAt: '2026-07-18T18:24:14.479Z' vendor: Red Hat product: Red Hat Enterprise Linux BaseOS (v. 10) affected: - enterprise_linux 9 - enterprise_linux_appstream_eus_v_10_0 - enterprise_linux_appstream_v_10 - enterprise_linux_appstream_v_9 - enterprise_linux_baseos_eus_v_10_0 - enterprise_linux_baseos_v_10 - enterprise_linux_baseos_v_9 - enterprise_linux_codeready_linux_builder_eus_v_10_0 - enterprise_linux_codeready_linux_builder_v_10 - enterprise_linux_codeready_linux_builder_v_9 - enterprise_linux_real_time_for_nfv_eus_v_10_0 - enterprise_linux_real_time_for_nfv_v_10 - enterprise_linux_real_time_for_nfv_v_9 - enterprise_linux_real_time_eus_v_10_0 - enterprise_linux_real_time_v_10 - enterprise_linux_real_time_v_9 patched: - enterprise_linux_appstream_eus_v_10_0 - enterprise_linux_appstream_v_10 - enterprise_linux_appstream_v_9 - enterprise_linux_baseos_eus_v_10_0 - enterprise_linux_baseos_v_10 - enterprise_linux_baseos_v_9 - enterprise_linux_codeready_linux_builder_eus_v_10_0 - enterprise_linux_codeready_linux_builder_v_10 - enterprise_linux_codeready_linux_builder_v_9 - enterprise_linux_real_time_for_nfv_eus_v_10_0 - enterprise_linux_real_time_for_nfv_v_10 - enterprise_linux_real_time_for_nfv_v_9 - enterprise_linux_real_time_eus_v_10_0 - enterprise_linux_real_time_v_10 - enterprise_linux_real_time_v_9 cwe: - CWE-131 --- ## Overview 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. ## Remediation Refer to the linked advisories for vendor-supplied fixes and affected version ranges. ## Vendor advisories - **RHSA-2026:35840** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v. 10.0), Red Hat Enterprise Linux BaseOS EUS (v. 10.0), Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0), Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0), Red Hat Enterprise Linux Real Time EUS (v. 10.0) · released 2026-07-06 · [advisory](https://access.redhat.com/errata/RHSA-2026:35840) - **RHSA-2026:34911** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10), Red Hat Enterprise Linux Real Time for NFV (v. 10), Red Hat Enterprise Linux Real Time (v. 10) · released 2026-07-02 · [advisory](https://access.redhat.com/errata/RHSA-2026:34911) - **RHSA-2026:66180** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux BaseOS (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9), Red Hat Enterprise Linux Real Time for NFV (v. 9), Red Hat Enterprise Linux Real Time (v. 9) · released 2026-09-10 · [advisory](https://access.redhat.com/errata/RHSA-2026:66180) - **Red Hat VEX** · Important · affected: Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 9 · updated 2026-09-10 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-53366.json)