PatchSiren cyber security CVE debrief

CVE-2025-38713 Cert Portal CVE debrief

CVE-2025-38713 describes a Linux kernel HFS+ bug in the hfsplus_readdir() path that can reach hfsplus_uni2asc() and trigger a slab-out-of-bounds read. The advisory text includes a KASAN report showing the fault during getdents64/readdir activity, and the issue is rated HIGH severity in the supplied CVSS vector. From a defensive standpoint, this is most relevant to systems that mount or process HFS+ filesystems, especially where local users or local filesystem access can exercise the path.

Vendor: Cert Portal
Product: Siemens SIMATIC CN 4100 vers:intdot/<5.0
CVSS: HIGH 7
CISA KEV: Not listed in stored evidence
Original CVE published: 2026-05-12
Original CVE updated: 2026-05-14
Advisory published: 2026-05-12
Advisory updated: 2026-05-14

Who should care

Linux kernel maintainers, distro security teams, embedded/system operators that mount HFS+ media, and incident responders responsible for hosts with filesystem support enabled.

Technical summary

The supplied source states that hfsplus_readdir() can call hfsplus_uni2asc() in a way that reads past the end of an allocated object, producing a slab-out-of-bounds read detected by KASAN. The trace shows the failure occurring during directory enumeration (getdents64/iterate_dir) and identifies a 2-byte read beyond the allocated region. The source CVSS vector is CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H, indicating local access and nontrivial conditions, but potentially serious impact once the path is reachable.

Defensive priority

High for Linux environments that may mount HFS+ volumes or otherwise exercise the hfsplus filesystem code path; lower operational priority on hosts that never use HFS+ support.

Recommended defensive actions

Apply the Linux kernel fix for the hfsplus_uni2asc() slab-out-of-bounds read through your vendor or distribution update channel as soon as it is available.
Prioritize patching hosts that can mount removable media or legacy HFS+ filesystems.
Review whether HFS+ support is needed on your systems and reduce exposure where it is not required.
Monitor kernel and distro security advisories for backported fixes and confirm the affected code path is included in your build.
Use general ICS/host hardening guidance from CISA for layered defense while patching is in progress.

Evidence notes

The supplied advisory text explicitly says: 'In the Linux kernel, the following vulnerability has been resolved: hfsplus: fix slab-out-of-bounds read in hfsplus_uni2asc().' It also includes a KASAN trace showing a slab-out-of-bounds read in hfsplus_uni2asc() during hfsplus_readdir()/getdents64. The source record was published 2026-05-12 and modified 2026-05-14. One important caveat: the structured product metadata references 'Siemens SIMATIC CN 4100 vers:intdot/<5.0,' but the vulnerability description itself is about the Linux kernel HFS+ filesystem. The vendor/product mapping is therefore low confidence and marked needs review in the supplied data.

Official resources

CISA's source advisory was published on 2026-05-12 and republished on 2026-05-14. The advisory narrative is about a Linux kernel HFS+ bug, while the structured product metadata names Siemens SIMATIC CN 4100; treat the product attribution as