CVE-2026-53362

Published Jul 4, 2026

Last updated 9 days ago

Exploit known CVSS high 7.8

Cloud

Container Security

IPv6

UDPv6

Overview

AI description

Automated description summarized from trusted sources.

CVE-2026-53362 describes a vulnerability within the Linux kernel's IPv6 networking subsystem, specifically concerning the `__ip6_append_data()` function. The flaw arises from incorrect accounting for "fraggap" (fragment gaps) when data is handled via the paged allocation path. This miscalculation occurs when `alloclen` and `pagedlen` are computed, particularly when `fraggap` is non-zero, leading to an undersized linear area and an overstated `pagedlen`. This accounting error can result in memory corruption, as bytes carried over from a previous `skb` (socket buffer) are copied past the intended boundary into the `skb_shared_info` structure. An unprivileged user can trigger this out-of-bounds write by utilizing a UDPv6 socket in conjunction with the `MSG_MORE` and `MSG_SPLICE_PAGES` flags. The issue was introduced by a commit aimed at avoiding partial copies for zero-copy operations, and a later commit allowed `MSG_SPLICE_PAGES` to proceed in this vulnerable state, making the corruption exploitable.

Description: In the Linux kernel, the following vulnerability has been resolved: ipv6: account for fraggap on the paged allocation path In __ip6_append_data(), when the paged-allocation branch is taken (MSG_MORE / NETIF_F_SG / large fraglen), alloclen and pagedlen are computed as alloclen = fragheaderlen + transhdrlen; pagedlen = datalen - transhdrlen; datalen already includes fraggap (datalen = length + fraggap). When fraggap is non-zero, this is not the first skb and transhdrlen is zero. The fraggap bytes carried over from the previous skb are copied just past the fragment headers in the new skb's linear area. The linear area is therefore undersized by fraggap bytes while pagedlen is overstated by the same amount, and the copy writes past skb->end into the trailing skb_shared_info. An unprivileged user can trigger this via a UDPv6 socket using MSG_MORE together with MSG_SPLICE_PAGES. The bad accounting was introduced by commit 773ba4fe9104 ("ipv6: avoid partial copy for zc"). Before commit ce650a166335 ("udp6: Fix __ip6_append_data()'s handling of MSG_SPLICE_PAGES"), the negative copy value caused -EINVAL to be returned. That later commit allowed MSG_SPLICE_PAGES to proceed in this case, making the corruption triggerable. 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. Since a negative copy is no longer expected for a valid MSG_SPLICE_PAGES case, remove the MSG_SPLICE_PAGES exception from the negative copy check.
Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status: Analyzed
Products: linux_kernel

Risk scores

CVSS 3.1

Type: Secondary
Base score: 7.8
Impact score: 5.9
Exploitability score: 1.8
Vector string: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Severity: HIGH

Known exploits

Data from CISA

Vulnerability name: Linux Kernel Unspecified Vulnerability
Exploit added on: Aug 27, 2026
Exploit action due: Aug 30, 2026
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.

Weaknesses

nvd@nist.gov: CWE-787
134c704f-9b21-4f2e-91b3-4a467353bcc0: CWE-122

Hype score: Not currently trending

Configurations

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References

Sources include official advisories and independent security research.