# CVE-2025-68774: hfsplus: fix missing hfs_bnode_get() in __hfs_bnode_create

> A race condition in the Linux kernel HFS+ filesystem can cause a kernel panic when concurrent threads create the same bnode, leading to denial of service.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 13 Jan 2026
- **Updated:** 5 Aug 2026
- **Also known as:** AZL-74445, BELL-CVE-2025-68774, DEBIAN-CVE-2025-68774, GHSA-2wrv-52xx-6xxv, ROOT-OS-DEBIAN-11-CVE-2025-68774, ROOT-OS-DEBIAN-12-CVE-2025-68774, ROOT-OS-DEBIAN-13-CVE-2025-68774, ROOT-OS-UBUNTU-2204-CVE-2025-68774, ROOT-OS-UBUNTU-2404-CVE-2025-68774, UBUNTU-CVE-2025-68774

## What is CVE-2025-68774?

CVE-2025-68774 is a high-severity vulnerability in Linux, published on 13 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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

hfsplus: fix missing hfs_bnode_get() in __hfs_bnode_create

When sync() and link() are called concurrently, both threads may
enter hfs_bnode_find() without finding the node in the hash table
and proceed to create it.

Thread A:
  hfsplus_write_inode()
    -> hfsplus_write_system_inode()
      -> hfs_btree_write()
        -> hfs_bnode_find(tree, 0)
          -> __hfs_bnode_create(tree, 0)

Thread B:
  hfsplus_create_cat()
    -> hfs_brec_insert()
      -> hfs_bnode_split()
        -> hfs_bmap_alloc()
          -> hfs_bnode_find(tree, 0)
            -> __hfs_bnode_create(tree, 0)

In this case, thread A creates the bnode, sets refcnt=1, and hashes it.
Thread B also tries to create the same bnode, notices it has already
been inserted, drops its own instance, and uses the hashed one without
getting the node.

```

	node2 = hfs_bnode_findhash(tree, cnid);
	if (!node2) {                                 <- Thread A
		hash = hfs_bnode_hash(cnid);
		node->next_hash = tree->node_hash[hash];
		tree->node_hash[hash] = node;
		tree->node_hash_cnt++;
	} else {                                      <- Thread B
		spin_unlock(&tree->hash_lock);
		kfree(node);
		wait_event(node2->lock_wq,
			!test_bit(HFS_BNODE_NEW, &node2->flags));
		return node2;
	}
```

However, hfs_bnode_find() requires each call to take a reference.
Here both threads end up setting refcnt=1. When they later put the node,
this triggers:

BUG_ON(!atomic_read(&node->refcnt))

In this scenario, Thread B in fact finds the node in the hash table
rather than creating a new one, and thus must take a reference.

Fix this by calling hfs_bnode_get() when reusing a bnode newly created by
another thread to ensure the refcount is updated correctly.

A similar bug was fixed in HFS long ago in commit
a9dc087fd3c4 ("fix missing hfs_bnode_get() in __hfs_bnode_create")
but the same issue remained in HFS+ until now.

## Which versions are affected by CVE-2025-68774?


## How do I fix CVE-2025-68774?

Apply the vendor's patch.

## Is CVE-2025-68774 being exploited?

There is no known exploitation of CVE-2025-68774 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-68774 and fix it if it is affected.

What it is: CVE-2025-68774 is a high-severity vulnerability in Linux, published on 13 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-68774 in the wild and no public exploit code.

Affected product: Linux. 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-2025-68774/ (Markdown: https://insights.sbomify.com/CVE-2025-68774/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-68774
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-68774
- OSV: https://osv.dev/vulnerability/CVE-2025-68774

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-68774/
Summaries are generated and may contain mistakes; the official description above is the record.