OpenWrt Patches ubusd RCE (CVE-2025-62526) and Kernel Memory Leak in DSL Driver (CVE-2025-62525) — What You Must Do Now By CyberDudeBivash

TL;DR — Quick summary

OpenWrt released v24.10.4 to fix two high-severity vulnerabilities: a heap-buffer overflow in ubusd (CVE-2025-62526) that can lead to remote code execution in the ubus daemon, and a kernel memory read/write issue in the ltq-ptm DSL driver (CVE-2025-62525) that permits local attackers to read/write arbitrary kernel memory (possible sandbox escape / local privilege escalation). Both issues are fixed in OpenWrt 24.10.4 — upgrade immediately if you run affected builds or images. OpenWrt+2NVD+2

Background & timeline

Advisory / Release: OpenWrt published security advisories and pushed the fixes in the 24.10.4 release on 22 October 2025. OpenWrt+1
CVE identifiers: CVE-2025-62526 (ubusd heap buffer overflow → RCE context) and CVE-2025-62525 (ltq-ptm DSL driver kernel memory R/W → local privilege escalation). Official CVE records are available at NVD and OpenWrt advisories. NVD+1

Affected components & scope

CVE-2025-62526 (ubusd — heap buffer overflow / RCE)

Affects ubusd‘s event-registration parsing code in OpenWrt versions prior to 24.10.4. The bug occurs before ACL checks are enforced, so any ubus client (including local processes and possibly unauthenticated/exposed clients depending on device config) can send a specially crafted subscription message triggering heap corruption and potentially arbitrary code execution in the ubus daemon context. This also bypasses listen ACLs. NVD+1

CVE-2025-62525 (ltq-ptm — kernel memory read/write / local privilege escalation)

The ltq-ptm driver’s ioctl handling on Lantiq (xrx200, danube, Amazon/Lantiq/MaxLinear SoCs) in PTM mode mishandles parameters enabling local users to read/write kernel memory via driver ioctls. This primarily affects devices using the lantiq target with PTM mode; ATM and some hardware (e.g., VRX518) are not affected. OpenWrt fixes this in 24.10.4. NVD+1

Why this matters (risk and exploitability)

CVE-2025-62526 is particularly dangerous because the heap overflow is processed before ACL enforcement and from the ubus interface that many system components use — meaning a local process (or in some misconfigured devices, a remote component) can potentially get code execution in a privileged process (ubusd). The practical result: persistent compromise, arbitrary command execution as the ubus daemon user, and lateral escalation inside the router firmware. OpenWrt
CVE-2025-62525 allows local kernel memory R/W — a classic stepping stone for sandbox escape and privilege escalation: attackers that can already run code on a device (e.g., through another bug, malicious package, or compromised service) can elevate privileges or tamper with kernel structures. NVD

Industry reporting flags both flaws as high-risk and urges immediate upgrade of OpenWrt images. heise online

Technical analysis (what’s happening under the hood)

ubusd heap overflow (CVE-2025-62526)

The vulnerability lies in how ubusd parses event subscription requests. A crafted subscription message (malformed length or header fields) leads to a heap buffer overflow. Because parsing happens prior to ACL/listen checks, the malformed message is processed even if the sender should not be authorized. Heap corruption can be manipulated to overwrite function pointers/structures used later by ubusd, enabling code redirection within ubusd’s process context. OpenWrt advisory confirms the overflow and listen ACL bypass. OpenWrt

ltq-ptm driver kernel memory issue (CVE-2025-62525)

The ltq-ptm driver exposes ioctls intended for DSL datapath control. Improper bounds checking or misuse of user-supplied pointers inside ioctl handlers permits arbitrary kernel memory read/write. A local attacker with access to the device’s userland can call these ioctls to read or overwrite kernel memory, potentially corrupting credentials, module pointers, or jump tables. OpenWrt notes the issue affects lantiq target families in PTM mode and is patched in 24.10.4. NVD

Detection & Indicators of Compromise (IoCs)

No public exploit PoC has been widely published at time of writing, but you should look for:

Unexpected or unknown ubus subscription messages in logs (if you log ubus traffic).
Crashes or restarts of ubusd, logd, or services dependent on ubus.
Unexplained privilege escalation behavior or odd kernel OOPS messages pointing to ltq_ptm/DSL ioctls in dmesg.
New or modified scheduled tasks, unauthorized network connections, or unusual persistent processes on routers.

Log and telemetry checks:

logread or dmesg for ubus/ubusd backtraces or kernel OOPS.
Monitoring for restarts of ubusd (systemd/sysv style supervision may attempt restarts).
Look for unknown uses of ioctl on /dev/ devices related to DSL/PTM if you have kernel tracing.

(Use these as starting signals — exploit patterns evolve quickly; prioritize patching.) OpenWrt+1

Immediate mitigation & remediation (what to do — step by step)

1. Prioritize patching → Upgrade to OpenWrt 24.10.4 (or later) immediately

OpenWrt fixed both issues in 24.10.4. Wherever possible, upgrade devices to official 24.10.4 images from the OpenWrt release page or vendor images that incorporate the patch. If you manage fleets, schedule an emergency rollout. OpenWrt+1

Standard safe upgrade workflow (recommended):

Backup current configuration: sysupgrade -b /tmp/backup.tar.gz or use LuCI backup.
Download the correct sysupgrade image (matching device/board) from OpenWrt releases (24.10.4).
Verify the image checksum.
Upload and run sysupgrade <image_file> (or use LuCI → System → Backup / Flash Firmware).
Reboot and validate system services (ubusd, dmesg, opkg list-installed).
Restore config if necessary and confirm normal operation.

2. If you cannot upgrade immediately (temporary mitigations):

Limit access to management interfaces: ensure ubus/ubusd endpoints are not exposed to WAN. Disable remote management or firewall off any admin/management ports. (This reduces attack surface but is not a fix.) OpenWrt
Restrict untrusted packages or containers that may interact with ubus. Remove unnecessary third-party packages that open ubus clients.
For multi-tenant embedded deployments, isolate user processes and scrutinize services that speak to ubus.

3. For devices using Lantiq PTM DSL hardware (CVE-2025-62525):

Upgrade as above. There are no workarounds listed in the advisory; isolating untrusted local accounts and ensuring no untrusted code runs on the device is the only short-term measure. NVD

What operators & vendors should do

Vendors shipping OpenWrt-based firmware should integrate the 24.10.4 fixes and publish updated vendor images — push OTA updates to customers. GitHub
Enterprise admins / MSSPs should scan their device inventories for OpenWrt versions < 24.10.4, prioritize remote and edge devices, and schedule emergency updates.
Security teams: add detection signatures to EDR/NTA for abnormal ubus traffic patterns and watch for kernel OOPS tied to ltq_ptm.

Attribution & public reporting

At this time the OpenWrt advisory and CVE entries provide the authoritative technical descriptions; there are no confirmed public mass-exploitation reports yet, but multiple security news outlets recommended immediate patching given the severity and nature of the bugs. OpenWrt+1

References (authoritative)

OpenWrt Security Advisory — ubusd: heap buffer overflow (2025-10-22). OpenWrt
NVD — CVE-2025-62526 (ubusd heap buffer overflow). NVD
NVD — CVE-2025-62525 (ltq-ptm kernel memory R/W). NVD
OpenWrt 24.10.4 release notes / GitHub release changelog. GitHub+1
Heise / industry writeups recommending immediate upgrades. heise online

Quick publish-ready banner spec (CyberDudeBivash)

Hero image idea: stylized OpenWrt router with warning overlay, small ubus/daemon icon and kernel chip graphic.
Banner text (headline): “Patch Now — OpenWrt Fixes ubusd RCE (CVE-2025-62526) & DSL Kernel Leak (CVE-2025-62525)”
Branding: place official CyberDudeBivash logo at top-right (use /mnt/data/CYBERDUDEBIVASH-LOGO.png), include URLs cyberdudebivash.com | cyberbivash.blogspot.com bottom-left.
CTA button: “Download 24.10.4 Images & Patching Guide” → link to OpenWrt release notes / our internal patch guide.
Colors: deep blue headline block + neon orange alert accent (fits CyberDudeBivash aesthetic).

Cyberdudebivash