mediasoup 3.20.3 released with an important SCTP fix

ibc · June 4, 2026, 5:51pm

mediasoup 3.20.3 ahs been released with an important SCTP bug fix:

github.com/versatica/mediasoup

Fix SCTP crash when the t3-rtx timer expires (#1822)

v3 ← fix-sctp-crash-when-t3-rtx-timer-expires

opened 04:42PM - 04 Jun 26 UTC

ibc

+61 -28

# Details - The mediasoup SCTP stack aborts the process under some scenarios …when the SCTP t3-rtx timer expires: ``` mediasoup:mediasoup:ERROR:Worker (ABORT) RTC::SCTP::AssociationListenerDeferrer::OnAssociationStreamBufferedAmountLow() | failed assertion this->ready: not ready ``` - The problem is that timers in `TransmissionControlBlock` (t3-rtx, delayed-ack), `HeartbeatHandler` and `StreamResetHandler` are direct entry points invoked by libuv but, unlike in libwebrtc/dcsctp, which handles all timers through `DcSctpSocket::HandleTimeout()` and creates a `CallbackDeferrer::ScopedDeferrer` there, these handlers in mediasoup's SCTP stack don't open the deferrer scope. When a SCTP t3-rtx timer expires it ends up invoking a deferred callback (e.g. `OnAssociationStreamBufferedAmountLow()` via `SendBufferedPackets()`) and triggers a failed assertion on `this->ready` and aborts the worker. - The fix: Each component owning its own timers now opens an `AssociationListenerDeferrer::ScopedDeferrer` at the start of its timer handlers (`OnT3RtxTimer()`/`OnDelayedAckTimer()`, `OnIntervalTimer()`/`OnTimeoutTimer()`, `OnReConfigTimer()`), just like `Association` already does in its `OnXxxxTimer()` callbacks. To allow this, the argument and member change from `AssociationListenerInterface&` to `AssociationListenerDeferrer&`. - _NOTE:_ `PacketSender` and `RetransmissionQueue` keep the `AssociationListenerInterface` class since they are not entry points. - _NOTE:_ `PacketSender` invokes `this->associationListener.OnAssociationSendData()`, however such a callback is not deferred so we are good. Similar stuff for `RetransmissionQueue`. - Test updated.

Please upgrade ASAP if you rely on SCTP/DataChannels in mediasoup >= 3.20.0.

Rust crates also updated.

system · June 6, 2026, 5:52pm

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mediasoup 3.20.3 released with an important SCTP fix

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