CVE-2025-32898: KDE Connect Auth Bypass Vulnerability

CVE-2025-32898 Overview

CVE-2025-32898 affects the KDE Connect device pairing protocol across multiple platforms. The verification-code mechanism used during device pairing relies on only 8 characters, creating a search space small enough for brute-force attacks. An attacker on an adjacent network can attempt to guess the verification code and complete an unauthorized pairing. The flaw maps to CWE-331: Insufficient Entropy and impacts KDE Connect clients on Android, desktop Linux, iOS, as well as the Valent and GSConnect implementations.

Critical Impact
An adjacent-network attacker can brute-force the KDE Connect pairing code to establish an unauthorized trust relationship with a target device, leading to limited exposure of shared data and device functionality.

Affected Products

KDE Connect before 1.33.0 on Android
KDE Connect before 25.04 on desktop and KDE Connect before 0.5 on iOS
Valent before 1.0.0.alpha.47 and GSConnect before 59

Discovery Timeline

2025-04-18 - KDE publishes Security Advisory 20250418-3 and releases fixed versions
2025-12-05 - CVE-2025-32898 published to the National Vulnerability Database (NVD)
2026-09-25 - Last updated in NVD database

Technical Details for CVE-2025-32898

Vulnerability Analysis

KDE Connect links phones and desktops over a local network to share files, notifications, clipboard contents, and input events. Pairing establishes a trust relationship between two devices using a verification code that the user confirms on both ends.

The affected protocol constrains that verification code to only 8 characters. The resulting entropy is low enough that an attacker who can reach the pairing service over an adjacent network can enumerate candidate codes until one succeeds. A successful brute force completes pairing without the legitimate user approving the attacker's device.

The weakness is a cryptographic design flaw rather than a memory-safety or injection bug. It falls under CWE-331: Insufficient Entropy, where the generated secret does not contain enough randomness to resist guessing within a practical window.

Root Cause

The verification code generated during the KDE Connect handshake is too short. An 8-character code drawn from a limited alphabet produces a key space that attackers can exhaustively search before the user cancels or completes pairing. The protocol also lacks sufficient rate limiting or binding to reject repeated guessing attempts.

Attack Vector

Exploitation requires network adjacency, such as the same Wi-Fi segment or local subnet, matching the AV:A attack vector. The attacker interacts with the KDE Connect discovery and pairing service on a victim device and submits guessed verification codes. On success, the attacker's device is treated as paired and gains access to functionality the user has granted to paired peers, including file sharing, clipboard contents, and remote input depending on configuration.

No verified public exploit code is available. See the KDE Security Advisory 20250418-3 for the vendor's technical description.

Detection Methods for CVE-2025-32898

Indicators of Compromise

Unexpected paired devices appearing in the KDE Connect, Valent, or GSConnect device list.
Repeated inbound pairing requests to KDE Connect TCP/UDP port 1716 from unfamiliar hosts on the local network.
File transfer, clipboard sync, or remote input events originating from devices the user did not approve.

Detection Strategies

Monitor host firewall and endpoint telemetry for high volumes of connections to local port 1716 from a single adjacent host.
Audit the KDE Connect trusted devices configuration on endpoints and compare against an approved inventory.
Correlate wireless or switch logs with endpoint pairing events to identify brute-force patterns originating from guest or untrusted network segments.

Monitoring Recommendations

Alert on new entries written to KDE Connect trusted device stores on Linux, Android, and iOS endpoints.
Track process and network activity for kdeconnectd, valent, and GSConnect extension processes to detect anomalous pairing bursts.
Review Wi-Fi segmentation and guest network isolation to limit which hosts can reach KDE Connect services.

How to Mitigate CVE-2025-32898

Immediate Actions Required

Upgrade KDE Connect to 1.33.0 or later on Android, and to 25.04 or later on desktop.
Upgrade KDE Connect on iOS to 0.5 or later, Valent to 1.0.0.alpha.47 or later, and GSConnect to version 59 or later.
Review paired device lists on all endpoints and remove any entries that are not recognized.

Patch Information

KDE addressed the issue in the releases listed in KDE Security Advisory 20250418-3. The fix increases the verification-code entropy so that brute-force enumeration during the pairing window is no longer practical. Downstream projects Valent and GSConnect shipped matching updates in 1.0.0.alpha.47 and v59 respectively.

Workarounds

Disable KDE Connect, Valent, or GSConnect on untrusted networks until patched versions are deployed.
Restrict KDE Connect traffic on TCP and UDP port 1716 with a host firewall so that only known management hosts can initiate pairing.
Place IoT, guest, and bring-your-own devices on isolated VLANs to prevent adjacent-network reach to developer workstations running KDE Connect.

bash

# Example: block inbound KDE Connect pairing on Linux until patched
sudo nft add rule inet filter input tcp dport 1716 drop
sudo nft add rule inet filter input udp dport 1716 drop