# CVE-2026-53362: ipv6: account for fraggap on the paged allocation path

> CVE-2026-53362: ipv6: account for fraggap on the paged allocation path. CVSS 7.8 (CVSS 3.1), in CISA KEV.

Canonical: https://rewindex.com/cve/CVE-2026-53362
Last updated: 2026-10-15T13:46:55Z

- Published: 2026-07-04 11:56 UTC · Updated: 2026-10-15 13:46 UTC · Assigner: Linux
- CVSS: 7.8 (CVSS 3.1) · Severity: High · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS: 0.71%, 53th percentile (scored 2026-10-25)
- CISA KEV: yes, added 2026-08-27, federal due date 2026-08-30, ransomware use: Unknown

## 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.

## CISA 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.

## Affected vendors and products

- Linux: Linux
- Siemens: SIMATIC S7-1500 TM MFP - GNU/Linux subsystem

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-53362)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-53362)
- [https://git.kernel.org/stable/c/14200d435af9a9eeb444f529fc2f689a236b7962](https://git.kernel.org/stable/c/14200d435af9a9eeb444f529fc2f689a236b7962)
- [https://git.kernel.org/stable/c/46f201f8b4c39633a1fa3dc12459f506d470993d](https://git.kernel.org/stable/c/46f201f8b4c39633a1fa3dc12459f506d470993d)
- [https://git.kernel.org/stable/c/6374fb9edf72c67a118a2c214a0dddd04c921e0a](https://git.kernel.org/stable/c/6374fb9edf72c67a118a2c214a0dddd04c921e0a)
- [https://git.kernel.org/stable/c/65fb14cbebb0cd0eff903a22d33537ddc8b95769](https://git.kernel.org/stable/c/65fb14cbebb0cd0eff903a22d33537ddc8b95769)
- [https://git.kernel.org/stable/c/736b380e28d0480c7bc3e022f1950f31fe53a7c5](https://git.kernel.org/stable/c/736b380e28d0480c7bc3e022f1950f31fe53a7c5)
- [https://git.kernel.org/stable/c/e9eacf19281ea2498b36291b56c9606118c2d74e](https://git.kernel.org/stable/c/e9eacf19281ea2498b36291b56c9606118c2d74e)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-53362 · Markdown: https://rewindex.com/cve/CVE-2026-53362.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-53362 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:10:45.213Z