# CVE-2026-64322: udf: validate sparing table length as an entry count, not a byte count

> A crafted UDF image triggers out-of-bounds reads and writes in the Linux kernel UDF driver, potentially allowing code execution or system crashes.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Jul 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-93593, BELL-CVE-2026-64322, DEBIAN-CVE-2026-64322, GHSA-r2mg-8x37-x2q4, ROOT-OS-DEBIAN-12-CVE-2026-64322, ROOT-OS-UBUNTU-2204-CVE-2026-64322, UBUNTU-CVE-2026-64322

## What is CVE-2026-64322?

CVE-2026-64322 is a high-severity memory corruption vulnerability in Linux kernel, published on 25 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

udf: validate sparing table length as an entry count, not a byte count

udf_load_sparable_map() accepts a sparing table when

	sizeof(*st) + le16_to_cpu(st->reallocationTableLen) > sb->s_blocksize

is false, i.e. it treats reallocationTableLen as a number of BYTES that
must fit in the block.  But the table is walked as an array of 8-byte
sparingEntry elements:

	for (i = 0; i < le16_to_cpu(st->reallocationTableLen); i++) {
		struct sparingEntry *entry = &st->mapEntry[i];
		... entry->origLocation ...
	}

in udf_get_pblock_spar15() and udf_relocate_blocks().  A
reallocationTableLen of N therefore passes the check whenever
sizeof(*st) + N <= blocksize, yet the consumers index
sizeof(*st) + N * sizeof(struct sparingEntry) bytes -- up to ~8x the
block.  On a crafted UDF image this is an out-of-bounds read in
udf_get_pblock_spar15(); udf_relocate_blocks() additionally feeds the
same length to udf_update_tag(), whose crc_itu_t() reads far past the
block, and its memmove() through st->mapEntry[] is an out-of-bounds
write.

Validate reallocationTableLen as the entry count it is, with
struct_size().

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-64322?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-64322?

Apply the vendor's patch.

## Is CVE-2026-64322 being exploited?

There is no known exploitation of CVE-2026-64322 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-64322 and fix it if it is affected.

What it is: CVE-2026-64322 is a high-severity memory corruption vulnerability in Linux kernel, published on 25 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-64322 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-64322/ (Markdown: https://insights.sbomify.com/CVE-2026-64322/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64322
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64322
- OSV: https://osv.dev/vulnerability/CVE-2026-64322

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64322/
Summaries are generated and may contain mistakes; the official description above is the record.