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CVE-2026-53362Linux Kernel Unspecified Vulnerability

Patch nowHigh7.8Exploited, CISA due date 2026-08-30EPSS 0.71%, higher than 54% of scored CVEs

CVE-2026-53362 is a out-of-bounds write in Linux Kernel, rated high (7.8 on CVSS 3.1).

Why this priority: Exploited in the wild: listed in CISA's KEV catalog.

Published · Updated · NVD status: Analyzed

What it is

Code writes past the end of a buffer, corrupting memory in ways an attacker can often turn into code execution. A buffer on the heap overflows and corrupts neighbouring data structures.

How it is reached

An attacker can exploit it by someone who can already run code or sign in on the machine, with an ordinary user account, and nobody has to click anything.

What an attacker gains

A successful attack can read the data it protects, change data or behaviour and take it offline. In practice, this kind of flaw lets an attacker crash the process, read memory, or in the worst case run code.

Is it being exploited?

CISA added it to the Known Exploited Vulnerabilities catalog on 2026-08-27: it is being exploited in the wild. EPSS estimates a 0.71% chance of exploitation activity in the next 30 days, higher than 54% of scored CVEs.

What to do

  1. Treat it as urgent: it is on CISA's KEV list. CISA's deadline for US federal agencies: 2026-08-30.
  2. No fixed version is listed for Linux Kernel itself; fixed versions for the other affected products are listed on this page.
  3. Limit who can run code or sign in on the hosts that run it.
  4. Check exposed instances for signs of compromise, not only for the version.

Description from NVD

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.

What this means for your architecture.

A CVE names a product. Whether it matters depends on where that product sits in your systems: what reaches it, which trust boundary it guards and what it can reach once compromised. Veriom maps your components, their relationships and your trust boundaries from your code, cloud and delivery evidence, so you can see where a component like this sits. The radar itself does not look at your systems.

Components it touches

  • Network edge devices: VPNs, firewalls, routers and gateways. They sit between the internet and internal networks, so a flaw in one is often the first step into everything behind it.
  • Operating systems on servers, workstations or devices. Everything on the host inherits the flaw.
  • Native code: operating systems, browsers and firmware. The flaw sits wherever native code reads untrusted data.
  • Network appliances and media or file parsers. The flaw sits wherever native code reads untrusted data.

Trust boundaries in play

  • Host boundary. The attacker needs a foothold on the machine first; the flaw turns a small foothold into a bigger one.
  • Wherever native code reads untrusted data. An attacker who crosses it can crash the process, read memory, or in the worst case run code.

Questions to answer about your own systems

  • Where does Linux Kernel run in your systems, and at which version?
  • Which of those hosts also run code or users you do not fully trust?
  • What can it reach once compromised: which data stores, secrets and services?
See how Veriom maps an architectureTake the interactive tour

Read more

Sources

  • CVE records and CVSS scores from the NVD CVE API. This product uses the NVD API but is not endorsed or certified by the NVD.
  • Exploitation status from CISA’s Known Exploited Vulnerabilities catalog.
  • Exploit likelihood from FIRST’s Exploit Prediction Scoring System (EPSS), refreshed daily.
  • Explanations are written by Veriom from fixed templates over each record’s data, not by a person reviewing each CVE. Descriptions are quoted from the records as published.