Vulnerability Analysis Report – [CVE-2025-38676]-Linux kernel IOMMU (AMD) stack buffer overflow from kernel cmdline

Vulnerability: Linux kernel IOMMU (AMD) stack buffer overflow from kernel cmdline

CVE: CVE-2025-38676
Severity: Pending at NVD/CNA (VulDB lists as Critical)
Status: Resolved upstream; distributions are rolling out fixes
Affected: Linux kernel up to 6.17-rc2 (IOMMU/AMD path) NVD VulDB

Summary

The AMD IOMMU driver in the Linux kernel had a stack buffer overflow when parsing certain kernel command-line arguments. Under maximum-length input, the code could write one byte past the end of an internal buffer (the acpiid string). Upstream has merged a fix; distros will ship patched kernels. NVD SUSE

Technical Details (concise)

Component: iommu/amd
Bug class: Stack buffer overflow during cmdline parsing (off-by-one) → potential memory corruption early in boot. NVD SUSE
Scope: Reported against kernels ≤ 6.17-rc2; tagged CVE-2025-38676; fix is upstream. VulDB NVD
Patch signal: Public patch discussion/series referenced by kernel lists. Spinics

Note: The kernel cmdline is “considered trusted in most environments,” which lowers typical remote exploitability but still demands patching—especially for PXE/automated provisioning and multi-tenant/cloud images. NVD

Threat Model & Likely Attack Paths

Preconditions: Attacker can influence kernel boot parameters (e.g., insecure boot chain, compromised PXE/provisioning, physical console/bootloader access).
Realistic risk: Memory corruption at boot; potential for crash/DoS. Code-exec likelihood is unclear and environment-dependent; treat as defense-in-depth urgent. NVD SUSE

Mitigation & Patching

1) Patch priority (recommended order):

Update to a distro kernel containing the upstream fix (watch SUSE/Red Hat/Ubuntu advisories and apply as released). SUSE
For custom kernels: pull the upstream change set corresponding to “iommu/amd: Avoid stack buffer overflow from kernel cmdline,” rebuild, and redeploy. Spinics

2) Boot-chain hardening (defense in depth):

Lock down bootloader edits (GRUB password, UEFI firmware passwords, disable interactive editing).
Enforce Secure Boot, restrict unsigned kernels, and control PXE/provisioning pipelines.
Restrict kexec and enable kernel lockdown on production nodes.

3) Interim ops guidance (while awaiting vendor builds):

Ensure only approved cmdline parameters are used in images; avoid experimental/over-long AMD IOMMU parameter strings.
Track distro security feeds for the CVE and schedule emergency maintenance windows to roll kernels quickly. SUSE

Detection & Hunting

Signals: Early-boot panics/oops involving iommu/amd; abnormal behavior immediately after boot.
Where to look:
- Serial console logs / cloud init logs for boot failures.
- dmesg (post-boot) for IOMMU warnings or stack traces referencing IOMMU init.
Preventive controls: Protect/monitor image pipelines; verify cmdline in golden images (/proc/cmdline) matches a hardened baseline.

Risk Rating (CyberDudeBivash view)

Exploitability: Low–Medium (requires cmdline influence)
Impact: Medium–High (kernel-context corruption → potential DoS; worst-case memory safety risk)
Overall action: Patch ASAP across server, cloud, and VDI fleets.

Timeline (IST)

Aug 26, 2025: CVE appears on NVD (“New CVE received from kernel.org”), fix described. NVD
Aug 26–27, 2025: Vendor trackers (SUSE, VulDB, PT Security) reflect the issue and note upstream resolution. SUSE VulDB Dbugs

References

NVD: CVE-2025-38676 — description & upstream-resolved note. NVD
SUSE CVE tracker: Mirrors NVD text and fix status. SUSE
VulDB: Lists affected as Linux Kernel up to 6.17-rc2, flags Critical. VulDB
Kernel mailing list (patch thread): “[PATCH RESEND] iommu/amd: Avoid stack buffer overflow from kernel cmdline.” Spinics

CyberDudeBivash Recommendation

Treat this as a fast patch & harden event. Even if remote exploitation is unlikely, kernel memory safety bugs are a no-debate update—especially in cloud images and automated boot chains. Roll patched kernels, lock the boot path, and verify every image’s cmdline.

Author: CyberDudeBivash • Powered by: CyberDudeBivash
🌐 cyberdudebivash.com • cyberbivash.blogspot.com

#CyberDudeBivash #CVE202538676 #Linux #Kernel #IOMMU #MemorySafety #PatchNow

Cyberdudebivash