CVE-2026-53362
CVE-2026-53362 is a security flaw in Linux Kernel, the core of Linux, which runs most servers, Android phones and many home routers. Someone who already has a foothold can use Linux Kernel to take full control of the machine. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 27 Aug 2026.[1]
Linux Kernel is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. Fixed by 6 commits to Linux, in the releases that include them.
Description
CISA calls it an unspecified in Linux Kernel. In its words: “Linux Kernel contains an unspecified vulnerability that can allow for privilege escalation via IPv6 networking subsystem. This vulnerability can impact multiple products, including but not limited to Suse, Red Hat, and other products using Linux.”[1]
The CVE record adds: “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…”[2]
The underlying weakness is out-of-bounds write (CWE-787), heap buffer overflow (CWE-122), in MITRE’s list of common software weaknesses.
It scores 7.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by the organisation that published the CVE using CVSS 3.1.[2]
Affected versions
NVD’s record lists these fixed versions: in each line, everything before the version shown is affected.[2]
| Product | Fixed in |
|---|---|
| Linux | commit 14200d435af9 |
| Linux | commit 65fb14cbebb0 |
| Linux | commit 46f201f8b4c3 |
| Linux | commit 6374fb9edf72 |
| Linux | commit e9eacf19281e |
| Linux | commit 736b380e28d0 |
Most families won’t have Linux Kernel; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 27 Aug 2026, 54 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 30 Aug 2026 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at under 1%. That’s in the top 47% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
Linux has published a fix or advice.[3] CISA’s 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).”[1]
- Check whether you use it.Linux Kernel is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
- Send this page to your IT person.Ask them to confirm it’s fixed (fixed by 6 commits to Linux, in the releases that include them), or not in use. CISA gave US government agencies until 30 Aug 2026 to fix it.
- If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.
You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 7.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at under 1%.[4] |
See also
Other Linux Kernel flaws
- CVE-2026-46300: missing initialization of a variable ·
- CVE-2026-53266: out-of-bounds write ·
- CVE-2025-39964: race condition ·
- CVE-2025-39682: improper check for unusual or exceptional conditions ·
- CVE-2022-0995: out-of-bounds write ·
- CVE-2022-0492: improper authentication ·
Other out-of-bounds write flaws
- CVE-2026-86950, Apple devices: out-of-bounds write ·
- CVE-2026-87491, Chrome and other Chromium browsers: out of bounds write ·
- CVE-2026-11645, Chrome and other Chromium browsers: out-of-bounds read and write ·
- CVE-2026-0300, Palo Alto Networks PAN-OS: out-of-bounds write ·
- CVE-2026-3909, Google Skia: out-of-bounds write ·
Added the same day
- CVE-2026-66384, JFrog Artifactory: improper limitation of a pathname to a restricted directory ·
- CVE-2023-49105, ownCloud: improper authentication ·
Every Linux flaw on CISA’s list · Everything added in August 2026
References
- ^ Cybersecurity and Infrastructure Security Agency. “Linux Kernel Unspecified Vulnerability”. Known Exploited Vulnerabilities Catalog, added 27 Aug 2026.
- ^ National Institute of Standards and Technology. “CVE-2026-53362 Detail”. National Vulnerability Database, published 4 Jul 2026.
- ^ Linux. Advisories and fixes: git.kernel.org, git.kernel.org, git.kernel.org, git.kernel.org, git.kernel.org, and 1 more on NVD’s record.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.007, percentile 53.5, 31 Oct 2026.
- CVE Program. “CVE-2026-53362”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.