CVE-2026-53362

Linux Kernel Unspecified Vulnerability

Actively exploited (CISA KEV) High 7.8 CVSS 3.1

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.

Description as published by the source, in English.

Key facts

Published: 2026-07-04
Last modified: 2026-08-28
Assigned by: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Scored by: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Probability of exploitation: 0.3 % higher than 18 % of all known vulnerabilities
EPSS, next 30 days, model v2026.06.15
Fix available: Yes, see references

Actively exploited

CISA added this vulnerability to the Known Exploited Vulnerabilities catalogue on 2026-08-27, with a remediation deadline of 2026-08-30 for US federal agencies.

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 products

Vendor	Product	Versions	Status
Linux	Linux Kernel	≥ 6.0, < 6.1.177	Affected
Linux	Linux Kernel	≥ 6.13, < 6.18.38	Affected
Linux	Linux Kernel	≥ 6.19, < 7.1.3	Affected
Linux	Linux Kernel	≥ 6.2, < 6.6.144	Affected
Linux	Linux Kernel	≥ 6.7, < 6.12.95	Affected

Weakness type

CWE-787: Out-of-bounds Write
The product writes data past the end, or before the beginning, of the intended buffer.
CWE-122: Heap-based Buffer Overflow
A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

References

Related at Berigo

Articles

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CISA has added six vulnerabilities to its Known Exploited Vulnerabilities catalogue. Five were published between 2015 and 2022, and three grant nothi…
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Does this affect you?

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Sources and freshness

CVE

What it is: A reference number naming one specific vulnerability, for example CVE-2024-9474.
What it tells you: Which vulnerability we are talking about, and in which product.
What it does NOT tell you: Nothing about how serious it is, whether anyone is exploiting it, or whether it concerns you.
Why it matters: Without a shared number, vendor, authority and tooling cannot discuss the same flaw.
Used with the others: The number is the key. NVD, KEV and EPSS all describe the same CVE.

NVD CWE CISA KEV EPSS

How to read this together

No single value should be used on its own. A high CVSS score does not mean a vulnerability is being exploited, and a low one does not mean it is harmless. The four sources answer four different questions.

CVE names the specific vulnerability.
NVD adds severity and technical detail about it.
CWE describes the type of mistake behind it.
CISA KEV shows that it is already being exploited.
EPSS estimates how likely exploitation is soon.

The order that decides what is urgent

Do you actually have the product?
Is the version you run affected?
Is it listed in CISA KEV?
Does it have a high EPSS score?
Is the system reachable from the internet or from others?
How important is the system to the business?
Are there compensating controls already in place?

The first two questions are not about the vulnerability at all. They are about you, and they remove most of the list before you start.

A short example

Fix this week

CVSS 6,5 (medium)

In CISA KEV: yes
EPSS: 94 per cent
A firewall facing the internet

Can be scheduled

CVSS 9,8 (critical)

In CISA KEV: no
EPSS: 0,04 per cent
A test server with no internet access

Sorted by CVSS alone, the one on the right comes first. It is the more serious flaw in theory. But the one on the left is being used against real organisations right now, and it sits where an attacker can reach it. That is the one to fix first.

The critical one still has to be fixed. It just does not have to be fixed today.

This product uses the NVD API but is not endorsed or certified by the NVD. CVE and the CVE logo are registered trademarks of The MITRE Corporation; CVE records are used under the CVE Terms of Use. CWE is a trademark of The MITRE Corporation, used per the CWE Terms of Use. KEV data from CISA (CC0). Exploitation probability from EPSS, a FIRST.org project. Open-source package data from OSV and the GitHub Advisory Database (CC-BY 4.0).

Scores and vectors are shown as published by the sources. The ordering of results is Berigo's own editorial assessment, described on the search page, and is not NVD data. An empty result never means a system is safe.