# CVE-2026-46169: hfsplus: fix uninit-value by validating catalog record size

> A local attacker with mount privileges can trigger an uninitialized memory read in the HFS+ filesystem driver, potentially leaking kernel memory contents.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 28 May 2026
- **Updated:** 19 Jun 2026
- **Also known as:** BELL-CVE-2026-46169, DEBIAN-CVE-2026-46169, GHSA-wjh6-3xg7-c2h2, ROOT-OS-DEBIAN-11-CVE-2026-46169, ROOT-OS-DEBIAN-12-CVE-2026-46169, ROOT-OS-UBUNTU-2204-CVE-2026-46169, ROOT-OS-UBUNTU-2404-CVE-2026-46169, UBUNTU-CVE-2026-46169

## What is CVE-2026-46169?

CVE-2026-46169 is a medium-severity vulnerability in Linux kernel, published on 28 May 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:

hfsplus: fix uninit-value by validating catalog record size

Syzbot reported a KMSAN uninit-value issue in hfsplus_strcasecmp(). The
root cause is that hfs_brec_read() doesn't validate that the on-disk
record size matches the expected size for the record type being read.

When mounting a corrupted filesystem, hfs_brec_read() may read less data
than expected. For example, when reading a catalog thread record, the
debug output showed:

  HFSPLUS_BREC_READ: rec_len=520, fd->entrylength=26
  HFSPLUS_BREC_READ: WARNING - entrylength (26) < rec_len (520) - PARTIAL READ!

hfs_brec_read() only validates that entrylength is not greater than the
buffer size, but doesn't check if it's less than expected. It successfully
reads 26 bytes into a 520-byte structure and returns success, leaving 494
bytes uninitialized.

This uninitialized data in tmp.thread.nodeName then gets copied by
hfsplus_cat_build_key_uni() and used by hfsplus_strcasecmp(), triggering
the KMSAN warning when the uninitialized bytes are used as array indices
in case_fold().

Fix by introducing hfsplus_brec_read_cat() wrapper that:
1. Calls hfs_brec_read() to read the data
2. Validates the record size based on the type field:
   - Fixed size for folder and file records
   - Variable size for thread records (depends on string length)
3. Returns -EIO if size doesn't match expected

For thread records, check against HFSPLUS_MIN_THREAD_SZ before reading
nodeName.length to avoid reading uninitialized data at call sites that
don't zero-initialize the entry structure.

Also initialize the tmp variable in hfsplus_find_cat() as defensive
programming to ensure no uninitialized data even if validation is
bypassed.

Weakness: CWE-908 (Use of Uninitialized Resource)

## Which versions are affected by CVE-2026-46169?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-46169?

Apply the vendor's patch.

## Is CVE-2026-46169 being exploited?

There is no known exploitation of CVE-2026-46169 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-2026-46169 and fix it if it is affected.

What it is: CVE-2026-46169 is a medium-severity vulnerability in Linux kernel, published on 28 May 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-2026-46169 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-2026-46169/ (Markdown: https://insights.sbomify.com/CVE-2026-46169/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46169
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46169
- OSV: https://osv.dev/vulnerability/CVE-2026-46169

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46169/
Summaries are generated and may contain mistakes; the official description above is the record.