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.
Published: 2026-07-16
Score: 7.8 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

The vulnerability originates from an incorrect calculation of allocation lengths in the IPv4 packet handling routine __ip_append_data() when the paged allocation path is used. Because the fraggap bytes are not accounted for properly, the subsequent copy operation may access a memory region that is larger or smaller than the allocated buffer, leading to a buffer overflow or underflow. This mismatch can corrupt kernel memory, potentially causing a kernel panic or, if an attacker manages to craft a packet that triggers the exploit, may be leveraged for privilege escalation. The impact is therefore memory corruption at the kernel level, which could result in a crash or unintended privilege escalation.

Affected Systems

All Linux kernel builds that include the __ip_append_data() implementation are affected, as indicated by the generic Linux kernel CPE. The CPE list also references Red Hat Enterprise Linux 10.2 and 10.0 EUS, indicating that those releases are included among the vulnerable systems. The absence of a specific version range in the CVE data implies that every kernel version prior to the patch that corrects the fraggap accounting is impacted.

Risk and Exploitability

The EPSS score of less than 1% indicates a very low likelihood of public exploitation at present, and the vulnerability is not listed in CISA’s KEV catalog. The CVSS score of 7.8 indicates strong potential for significant impact should the flaw be exploited. The likely attack vector is network‑based, requiring an attacker to send a specially crafted IPv4 packet processed by the kernel’s networking stack. The complexity of creating a packet that precisely triggers the miscalculation may limit exploitation, but the potential for a kernel crash or privilege escalation remains significant.

Generated by OpenCVE AI on August 3, 2026 at 02:58 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Apply an updated Linux kernel version that includes the fraggap accounting fix in __ip_append_data().
  • Reboot the system or restart network services to ensure the updated kernel is in use.
  • If applying the patch immediately is not possible, limit or filter inbound IPv4 traffic, or disable IP forwarding or VLAN filtering to reduce the likelihood of exercising the vulnerable code path.

Generated by OpenCVE AI on August 3, 2026 at 02:58 UTC.

Tracking

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4688-1 linux security update
Debian DLA Debian DLA DLA-4700-1 linux-6.1 security update
History

Fri, 24 Jul 2026 18:30:00 +0000


Fri, 24 Jul 2026 06:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-119

Sat, 18 Jul 2026 12:15:00 +0000

Type Values Removed Values Added
First Time appeared Redhat
Redhat enterprise Linux
Redhat enterprise Linux Eus
Weaknesses CWE-131
CPEs cpe:/o:redhat:enterprise_linux:10.2
cpe:/o:redhat:enterprise_linux_eus:10.0
Vendors & Products Redhat
Redhat enterprise Linux
Redhat enterprise Linux Eus
References
Metrics threat_severity

None

threat_severity

Moderate


Sat, 18 Jul 2026 08:00:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}


Fri, 17 Jul 2026 16:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-119

Thu, 16 Jul 2026 05:30:00 +0000

Type Values Removed Values Added
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.
Title ipv4: account for fraggap on the paged allocation path
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
Redhat Enterprise Linux Enterprise Linux Eus
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-07-24T14:33:54.829Z

Reserved: 2026-06-09T07:44:35.400Z

Link: CVE-2026-53366

cve-icon Vulnrichment

No data.

cve-icon NVD

No data.

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-07-16T00:00:00Z

Links: CVE-2026-53366 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-08-03T03:00:04Z

Weaknesses
  • CWE-131

    Incorrect Calculation of Buffer Size