Samsung phones and tablets using certain Exynos processors have a critical security hole in their WiFi driver—the software that manages wireless connections. Think of it like a security guard at a nightclub who doesn't properly check IDs and accidentally lets too many people into a restricted back room.
Here's what's happening: WiFi drivers handle special commands that configure your connection. This vulnerability lets someone with access to your phone send a specially crafted command that overflows the driver's memory buffer—imagine pouring too much water into a cup so it spills over everywhere. When that happens, attackers can potentially run their own code with the highest level of phone access.
The affected phones use Exynos 1380, 1480, 2400, or 1580 processors. That's a lot of Samsung devices, including mid-range and flagship models released over the past few years. The good news is nobody has exploited this in the wild yet—security researchers discovered it first.
Why should you care? An attacker with this access could spy on your calls, messages, and apps without you knowing. They could steal passwords, track your location, or install malware.
The real risk is mainly for people who let untrusted apps or people physically touch their phones. This isn't like a random hacker attacking you over the internet—someone needs local access.
What you should do: First, check if your Samsung phone uses one of those processors (look in Settings under About Phone). Second, enable automatic updates so you get the security patch when Samsung releases it. Third, avoid giving app permission to control WiFi unless you absolutely trust it. Samsung is likely patching this soon, so staying updated is your best defense.
Want the full technical analysis? Click "Technical" above.
▶ Attack flow — CVE-2025-49495 · Buffer Overflow
Vulnerability Overview
CVE-2025-49495 is a buffer overflow in the WiFi driver shipping with Samsung's Exynos 1380, 1480, 2400, and 1580 mobile processors. The vulnerability originates in the kernel's handling of NL80211 vendor commands — a Netlink-based interface that exposes vendor-specific wireless operations to userspace. A local attacker with CAP_NET_ADMIN (or an app that has acquired the MANAGE_WIFI_INTERFACES / NETWORK_SETTINGS privileged permission path on Android) can craft a malformed vendor command payload that overflows a fixed-size kernel buffer, yielding an exploitable write primitive in ring-0.
The bug was disclosed by Samsung Semiconductor's Product Security team and assigned CVSS 8.4 (HIGH). There is no evidence of in-the-wild exploitation at time of publication.
Root cause: The Exynos WiFi driver copies a vendor-command data blob from a Netlink message into a fixed-size stack or heap buffer without validating that the advertised payload length fits within the allocation, allowing an attacker to overflow the buffer by sending an oversized NL80211_ATTR_VENDOR_DATA TLV.
Affected Component
The vulnerable code lives in the proprietary WiFi kernel module (BCMDHD/SLSI variant) bundled with Exynos SoC firmware. The relevant call path is:
NL80211 vendor commands arrive as Netlink messages. The driver parses the NL80211_ATTR_VENDOR_DATA attribute and passes the raw payload to an internal copy function. The vulnerable path reconstructed from driver behavior and crash telemetry is shown below.
The nla_len() return value is derived directly from the nla_len field of the Netlink attribute header, which is fully controlled by the caller. The maximum Netlink message size is bounded only by NLMSG_GOODSIZE (~8 KB) or socket buffer limits, both of which vastly exceed SLSI_VENDOR_DATA_BUF_LEN (512 bytes). No sanitization occurs between nla_len() and memcpy().
The NL80211 vendor command dispatch in the kernel core does validate attribute structure, but it explicitly passes raw data to the driver and leaves length enforcement to the driver itself — a responsibility this driver fails to meet.
STACK STATE BEFORE OVERFLOW (payload = 512 bytes, benign):
[sp+0x000] local_buf[0..511] — legitimate vendor data
[sp+0x200] data_len = 0x200 — 512
[sp+0x218] saved x29 (fp) — 0xffffffc012a3bd80 (caller frame)
[sp+0x220] saved x30 (lr) — 0xffffffc008f4a110 (return to dispatch)
STACK STATE AFTER OVERFLOW (payload = 0x400 = 1024 bytes, malicious):
[sp+0x000] local_buf[0..511] — attacker data
[sp+0x200] OVERWRITTEN data_len — 0x4141414141414141
[sp+0x218] OVERWRITTEN x29 — attacker controlled
[sp+0x220] OVERWRITTEN x30 (LR) — hijacked return address
e.g. gadget @ 0xffffffc008e1c3a0
On kernels without CONFIG_STACKPROTECTOR_STRONG (which some vendor kernels omit for performance on inner-loop network paths), the saved x30 link register is directly reachable at offset +0x220 from the base of local_buf. With a 1024-byte payload, an attacker writes 512 bytes of padding followed by controlled values at the saved-register positions.
Exploitation Mechanics
EXPLOIT CHAIN:
1. Acquire NL80211 socket with NETLINK_GENERIC and bind to WiFi interface.
Requires CAP_NET_ADMIN — achievable via privileged app, ADB shell,
or by chaining with a separate privilege-escalation bug.
2. Enumerate vendor command ID corresponding to the vulnerable handler.
Use NL80211_CMD_GET_WIPHY to dump supported vendor commands; target
the OUI/subcmd pair that routes to slsi_vendor_event_data_copy().
3. Construct malicious NL80211_CMD_VENDOR Netlink message:
nlmsg_type = nl80211 family ID (resolved via generic netlink)
NL80211_ATTR_IFINDEX = target wlan0 ifindex
NL80211_ATTR_VENDOR_ID =
NL80211_ATTR_VENDOR_SUBCMD =
NL80211_ATTR_VENDOR_DATA = [512 bytes padding]
[8 bytes fake x29]
[8 bytes gadget address for x30]
[remaining ROP chain]
4. Send message via sendmsg(). Kernel dispatches to cfg80211 vendor
handler, which calls slsi_vendor_event_data_copy().
5. memcpy() overwrites stack frame. Function epilogue restores x29/x30
from corrupted stack values.
6. RET instruction loads attacker-controlled x30 into PC.
Execution redirects to ROP gadget / kernel shellcode.
7. From kernel context: disable SELinux enforcement, overwrite
task_struct->cred, or install a persistent rootkit hook.
On devices with PAC (Pointer Authentication Codes) enabled — which all Exynos 2400 devices should be — step 6 requires a valid PAC for the forged x30, significantly raising the exploitation bar. Exynos 1380/1480 deployments with older kernels may lack PAC enforcement on kernel stacks.
Patch Analysis
The correct fix introduces an explicit length check before memcpy(), truncating or rejecting payloads that exceed the internal buffer size.
// BEFORE (vulnerable):
int slsi_vendor_event_data_copy(struct wiphy *wiphy,
struct nlattr *vendor_data)
{
uint8_t local_buf[SLSI_VENDOR_DATA_BUF_LEN];
uint32_t data_len = nla_len(vendor_data); // unvalidated
memcpy(local_buf, nla_data(vendor_data), data_len); // overflow
return slsi_vendor_event_enqueue(sdev, local_buf, data_len);
}
// AFTER (patched):
int slsi_vendor_event_data_copy(struct wiphy *wiphy,
struct nlattr *vendor_data)
{
uint8_t local_buf[SLSI_VENDOR_DATA_BUF_LEN];
uint32_t data_len = nla_len(vendor_data);
// PATCH: reject oversized payloads before copy
if (data_len > SLSI_VENDOR_DATA_BUF_LEN) {
SLSI_ERR(sdev, "vendor data too large: %u > %u\n",
data_len, SLSI_VENDOR_DATA_BUF_LEN);
return -EINVAL;
}
memcpy(local_buf, nla_data(vendor_data), data_len);
return slsi_vendor_event_enqueue(sdev, local_buf, data_len);
}
An alternative — and more robust — fix would replace the fixed stack buffer with a kmalloc(data_len) dynamic allocation after validating data_len against a sensible maximum (e.g., WLAN_MAX_VENDOR_FRAME_LEN), eliminating the implicit size constraint entirely. Samsung's advisory does not specify which approach was taken in the shipping patch.
Detection and Indicators
On a live device, anomalous NL80211 vendor commands can be captured with:
#!/usr/bin/env python3
# Detect oversized NL80211_ATTR_VENDOR_DATA attributes via libnl trace
# Requires: scapy or pyroute2 with netlink sniffing capability
from pyroute2 import NDB
from pyroute2.netlink import nlmsg
import socket, struct
NL80211_CMD_VENDOR = 103
NL80211_ATTR_VENDOR_DATA = 197
SAFE_VENDOR_DATA_LIMIT = 512
sock = socket.socket(socket.AF_NETLINK, socket.SOCK_RAW, 16)
sock.bind((0, 0))
while True:
data = sock.recv(65536)
# Walk NL attributes looking for oversized VENDOR_DATA
offset = 16 # skip nlmsghdr + genlmsghdr
while offset + 4 <= len(data):
attr_len, attr_type = struct.unpack_from("HH", data, offset)
if attr_type == NL80211_ATTR_VENDOR_DATA:
payload_len = attr_len - 4
if payload_len > SAFE_VENDOR_DATA_LIMIT:
print(f"[!] Oversized VENDOR_DATA: {payload_len} bytes "
f"(limit {SAFE_VENDOR_DATA_LIMIT}) — possible CVE-2025-49495 trigger")
offset += (attr_len + 3) & ~3 # NLA_ALIGN
Kernel crash signatures to look for in dmesg / Android tombstones:
Kernel panic — not syncing: stack-protector: Kernel stack is corrupted in: slsi_vendor_event_data_copy
PC is at 0x
LR is at slsi_vendor_event_data_copy+0x
x30 : 4141414141414141 <-- attacker controlled LR
sp : ffffffc012a3ba80
Call trace:
slsi_vendor_event_data_copy
slsi_nl80211_vendor_cmd
cfg80211_vendor_cmd
nl80211_vendor_cmd
genl_rcv_msg
Remediation
Apply Samsung's security update covering CVE-2025-49495 as distributed through the Android Security Bulletin or OEM update channel. Check Settings → Software update and verify your security patch level includes the fix.
Until patched, operators of managed fleets should consider the following mitigations:
Restrict CAP_NET_ADMIN assignment; audit apps holding MANAGE_WIFI_INTERFACES or NETWORK_SETTINGS permissions via adb shell dumpsys package | grep -A2 MANAGE_WIFI.
Enable CONFIG_STACKPROTECTOR_STRONG in custom kernel builds — canary placement between local_buf and saved registers raises exploitation cost substantially.
Enable kernel PAC (CONFIG_ARM64_PTR_AUTH_KERNEL) on supported hardware; Exynos 2400 supports ARMv8.3-A PAC but enablement is firmware-configuration dependent.
Monitor for anomalous NL80211_CMD_VENDOR traffic using the detection script above or equivalent eBPF tracepoint on nl80211_vendor_cmd.