I found that some attackers are reportedly using custom UDP socket scripts and network packet tools during Telegram voice chats/groups to abuse network behavior and disrupt VC stability.
For example, I came across a simple UDP socket test script written in C language that sends packets over UDP (CoAP port testing). While this example itself is only a localhost test and not dangerous alone, similar modified scripts/tools can allegedly be abused by attackers for flooding or network-based disruption attempts.
Because of this abuse:
Group voice chats start lagging or glitching
Users get disconnected
VC becomes unstable or crashes
Communities are getting targeted repeatedly
Please investigate whether Telegram VC infrastructure has any vulnerability related to IP/network exposure or UDP abuse, and improve protection against such attacks.
This issue is actively affecting public groups and communities.
Steps to reproduce
Steps to reproduce:
Join or create a public Telegram group with Voice Chat enabled.
Start or join an active Voice Chat session.
After some time, malicious users begin targeting the VC using network/UDP abuse methods.
Voice Chat starts lagging, glitching, or disconnecting users.
Some users experience unstable audio, reconnect loops, or VC crashes.
Expected result:
Voice Chat should remain stable and protected against network abuse.
Actual result:
VC becomes unstable and users get disconnected due to possible abuse/exploit activity.
I already reported the DDoS issue to the Telegram team, but they still haven't fixed anything. This is really frustrating. Please fix it as soon as possible.
The issue is still reproducible as of September 2026. During active public Voice Chats, multiple participants can simultaneously become stuck on “Connecting…” or get disconnected. This continues despite restarting the Voice Chat and testing different networks/devices. Please investigate whether group Voice Chat participants can be exposed to direct UDP traffic or whether Telegram’s Voice Chat networking/relay infrastructure can be abused to cause packet flooding or connection disruption. Please also clarify whether there is an official way for group admins to force Voice Chats through Telegram relay infrastructure and prevent participant IP exposure.
This issue is still reproducible as of September 2026 and has not been fixed.
During Telegram Group Voice Chats, multiple participants can simultaneously become stuck on “Connecting…” or get disconnected/reconnected repeatedly. In some incidents, the problem affects a large portion of the Voice Chat at the same time.
We have tested different devices and network connections, restarted Voice Chats, and reproduced the issue multiple times.
There is also a concern about direct UDP connectivity and participant IP exposure. We suspect that the Voice Chat networking path may allow malicious users to abuse UDP traffic against participants and disrupt the Voice Chat.
Please investigate:
1. Whether Group Voice Chat participants can establish direct UDP connections that expose their public IP addresses.
2. Whether malicious participants can abuse this networking path to cause packet flooding or connection disruption.
3. Whether Telegram can provide a server-relay-only mode for Group Voice Chats, preventing direct participant-to-participant connectivity.
4. Whether additional server-side rate limiting or anti-DDoS protection can be applied to Group Voice Chat traffic.
The issue is still affecting active Voice Chats. Please investigate this as a potential networking/security issue rather than only a client-side connection problem.
Evidence: Screenshots and recordings can be provided showing multiple participants simultaneously stuck on “Connecting…” during the incident.
QnA
The fix is usually closing the voice chat and reopening it.
Please investigate whether group Voice Chat participants can be exposed to direct UDP traffic or whether Telegram’s Voice Chat networking/relay infrastructure can be abused to cause packet flooding or connection disruption.
Please also clarify whether there is an official way for group admins to force Voice Chats through Telegram relay infrastructure and prevent participant IP exposure.
This issue is still reproducible as of September 2026 and has not been fixed.
During Telegram Group Voice Chats, multiple participants can simultaneously become stuck on “Connecting…” or get disconnected/reconnected repeatedly. In some incidents, the problem affects a large portion of the Voice Chat at the same time.
We have tested different devices and network connections, restarted Voice Chats, and reproduced the issue multiple times.
There is also a concern about direct UDP connectivity and participant IP exposure. We suspect that the Voice Chat networking path may allow malicious users to abuse UDP traffic against participants and disrupt the Voice Chat.
Please investigate:
1. Whether Group Voice Chat participants can establish direct UDP connections that expose their public IP addresses.
2. Whether malicious participants can abuse this networking path to cause packet flooding or connection disruption.
3. Whether Telegram can provide a server-relay-only mode for Group Voice Chats, preventing direct participant-to-participant connectivity.
4. Whether additional server-side rate limiting or anti-DDoS protection can be applied to Group Voice Chat traffic.
The issue is still affecting active Voice Chats. Please investigate this as a potential networking/security issue rather than only a client-side connection problem.
Evidence: Screenshots and recordings can be provided showing multiple participants simultaneously stuck on “Connecting…” during the incident.