GHSA-qwfw-ggxw-577c — ex_webrtc
Fix: elixir-webrtc/ex_webrtc#250GHSA-qwfw-ggxw-577c is a CWE-295 vulnerability in ex_webrtc. A fix is available for ex_webrtc — see the affected versions and patch details below.
ex_webrtc client-role handshake is missing DTLS peer fingerprint validation
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-qwfw-ggxw-577c.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
ex_webrtc💧ex_webrtcReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Hex packages — download data is not available via public APIs for these ecosystems.
Description
Summary
Missing DTLS peer certificate fingerprint validation in the DTLS client (active) role removes one side of WebRTC's mutual authentication. The bug is not independently exploitable for media interception in standard deployments, but enables a full man-in-the-middle attack when chained with insecure signalling or a peer with similar validation gaps.
Details
ex_webrtc validates the DTLS peer's certificate fingerprint against the value advertised in the SDP offer/answer when acting as the DTLS server (passive role). When acting as the DTLS client (active role) -- the default when answering a remote offer with a=setup:actpass, which is what browsers always send -- the fingerprint check was skipped on the handshake-completion code path that returns no outgoing packets. This is the most common deployment mode (e.g., an SFU or media server answering a browser's offer).
All released versions prior to 0.15.1 and 0.16.1 are affected. No backports to older lines are planned -- users should upgrade to 0.15.1 or 0.16.1.
Impact
The bug eliminates one half of WebRTC's mutual DTLS authentication. The security of the media and data-channel encryption then rests entirely on the remote peer's fingerprint check.
On its own, the bug does not allow:
- Passive eavesdropping on SRTP media.
- A network-positioned attacker to intercept media against a standards-compliant browser peer over a TLS-protected signalling channel -- the browser's fingerprint check prevents the second leg of the MITM from succeeding.
The bug does enable a full MITM on media and data channels when combined with any of:
- Insecure signalling (HTTP / plain WebSocket) allowing SDP rewrite in transit.
- A compromised or malicious signalling server.
- A peer implementation with a similar fingerprint-validation gap.
Both audio/video media (SRTP) and data channels (SCTP-over-DTLS) are affected.
Patches
0.15.1(for the 0.15.x line)0.16.1(for the 0.16.x line)
Workarounds
None. Upgrade is required.
Resources
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💧Hex | ex_webrtc | all versions | 0.15.1mix deps.update ex_webrtc |
| 💧Hex | ex_webrtc | ≥ 0.16.0&&< 0.16.1 | 0.16.1mix deps.update ex_webrtc |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ex_webrtc, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update ex_webrtc to 0.15.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-qwfw-ggxw-577c 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-qwfw-ggxw-577c can be triaged on real exposure rather than presence alone.
Tailored to GHSA-qwfw-ggxw-577c. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-qwfw-ggxw-577c in your dependencies?
O3 Security finds GHSA-qwfw-ggxw-577c across Hex dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.