CVE-2026-54632 is a high-severity (CVSS 7.5) vulnerability in SIPSorcery. O3 Security confirms whether CVE-2026-54632 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
SIPSorcery: Malformed UDP packet on the RTP/ICE socket can remotely terminate a media session (DoS)
Real-World Exposure
SIPSorceryReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.
Description
Impact
A single malformed inbound UDP packet on the RTP/ICE socket can remotely terminate an active RTP or WebRTC media session. The packet receive handler indexes packet (and STUN attribute) bytes without sufficient length checks and throws, and the UDP receive loop converted any such exception into a channel Close rather than dropping the packet. One small, unauthenticated packet therefore ends the media session.
This is reachable during ICE connectivity checks — before the DTLS handshake and before any STUN MESSAGE-INTEGRITY verification. Because the RTP/ICE port is shared/advertised in the ICE candidates, a peer or on-path attacker can reach it (exposure is lower for a blind off-path attacker that must first learn the ephemeral port). Impact is availability only — no loss of confidentiality or integrity.
Affected versions
NuGet package SIPSorcery <= 10.0.8.
Patches
Fixed in 10.0.9.
Root cause
Two issues combine:
-
Unchecked indexing of untrusted bytes.
RTPChannel.OnRTPPacketReceivedreadpacket[1]after only checking the packet was non-empty, so a 1-byte packet threwIndexOutOfRangeException.STUNAttribute.ParseMessageAttributespassed anull/short value to the typed attribute parsers, andSTUNXORAddressAttribute(and the non-XORSTUNAddressAttribute) then readattributeValue[1],AsSpan(2)andAsSpan(4)with no length check. A STUN message carrying anXOR-MAPPED-ADDRESS,XOR-PEER-ADDRESSorXOR-RELAYED-ADDRESSattribute of length 0–7 threw (NullReferenceExceptionfor length 0,IndexOutOfRangeException/ArgumentOutOfRangeExceptionfor 1–7).
-
The UDP receive loop closed the channel on any exception. The catch-all in
UdpReceiver.EndReceiveFromcalledClose(), tearing down the channel, instead of dropping the offending packet and continuing. This was systemic: any unhandled exception anywhere in the packet pipeline (STUN, RTP, RTCP, DTLS demux, SRTP, TURN) became a channel teardown.
Fix
UdpReceiver.EndReceiveFrom: a non-socket exception now logs and drops the single packet and re-arms the receive loop (matching the existingSIPUDPChannelbehaviour), instead of closing the channel. Genuine socket failures continue to be handled separately.RTPChannel.OnRTPPacketReceived: requires a minimum packet length (RTPHeader.MIN_HEADER_LEN) before indexing the discriminator bytes.- STUN parsing:
ParseMessageAttributesvalidates each attribute value length and skips malformed/truncated attributes; the XOR/address attribute constructors validate length defensively;ParseSTUNMessageno longer dereferences a null attribute list.
Regression tests were added covering the 1-byte packet (channel stays open and remains usable), short/zero-length XOR address attributes (0–7 bytes), and truncated STUN messages.
Workarounds
None within the library short of upgrading. Restricting the RTP/ICE port to known peers at the network layer reduces exposure but does not eliminate it, since a negotiating peer can still trigger the condition.
Credit
Responsibly reported by Lokhesh Ujhoodha.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | SIPSorcery | all versions | 10.0.9 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for SIPSorcery. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update SIPSorcery to 10.0.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-54632 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-54632 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-54632. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-54632 in your dependencies?
O3 detects CVE-2026-54632 across NuGet dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.