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Unity Linux 20.1060a Security Update: kernel (UTSA-2026-014323)

medium Nessus Plugin ID 310376

Synopsis

The Unity Linux host is missing one or more security updates.

Description

The Unity Linux 20 host has a package installed that is affected by a vulnerability as referenced in the UTSA-2026-014323 advisory.

 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.

Tenable has extracted the preceding description block directly from the Unity Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Update the affected kernel package.

See Also

http://www.nessus.org/u?fde09acc

http://www.nessus.org/u?0af0a020

https://nvd.nist.gov/vuln/detail/CVE-2025-68774

Plugin Details

Severity: Medium

ID: 310376

File Name: unity_linux_UTSA-2026-014323.nasl

Version: 1.1

Type: Local

Published: 4/26/2026

Updated: 4/26/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.4

CVSS v2

Risk Factor: Low

Base Score: 3.8

Temporal Score: 2.8

Vector: CVSS2#AV:L/AC:H/Au:S/C:N/I:N/A:C

CVSS Score Source: CVE-2025-68774

CVSS v3

Risk Factor: Medium

Base Score: 4.7

Temporal Score: 4.1

Vector: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

Required KB Items: Host/local_checks_enabled, Host/cpu, Host/UOS-Server/release, Host/UOS-Server/rpm-list

Exploit Ease: No known exploits are available

Patch Publication Date: 4/26/2026

Vulnerability Publication Date: 1/13/2026

Reference Information

CVE: CVE-2025-68774