SIPSorcery: Malformed UDP packet on the RTP/ICE socket can remotely terminate a media session (DoS)GHSA-28gm-jrmw-xx93
HIGHFix: sipsorcery-org/sipsorcery#1677GHSA-28gm-jrmw-xx93 is a high-severity (CVSS 7.5) Improper Input Validation vulnerability in SIPSorcery. A fix is available for SIPSorcery — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-28gm-jrmw-xx93.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-28gm-jrmw-xx93 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 394,803 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
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 | 10.0.9dotnet add package SIPSorcery --version 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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update SIPSorcery to 10.0.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-28gm-jrmw-xx93 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.
Frequently Asked Questions
Is GHSA-28gm-jrmw-xx93 in your dependencies?
Find it across NuGet, including transitive dependencies.