CVE-2026-55663

MEDIUMPre-NVD 5.65.6—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.6 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2%, top 95% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
5.6EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.6Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

mediasoup is a WebRTC video conferencing system. From version 3.20.0 until 3.20.6 for the npm package and from 0.22.0 until 0.22.5 for the Rust crate, mediasoup's built-in SCTP stack authenticates state cookies using only the hardcoded msworker and 0xAD81 magic values instead of a per-instance secret and HMAC, contrary to RFC 9260 Section 5.1.3. The cookie structure and validation in worker/include/RTC/SCTP/association/StateCookie.hpp and worker/src/RTC/SCTP/association/StateCookie.cpp allow an on-path attacker targeting PlainTransport or PipeTransport with SCTP enabled and without DTLS protection to forge a COOKIE-ECHO whose packet verification tag matches the attacker-controlled localVerificationTag. The forged cookie passes StateCookie::IsMediasoupStateCookie() and Association::HandleReceivedCookieEchoChunk(), establishes an unauthorized SCTP association, and permits DataChannel message injection as a trusted peer. WebRtcTransport is not affected because its SCTP runs inside DTLS. This issue is fixed in npm version 3.20.6 and Rust crate version 0.22.5.

CVSS v3
5.6
EG Score
5.6(medium)
EG Risk
41(Track)
EG Risk 41/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity56% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
5%
KEV
Not listed

Published

August 25, 2026

Last Modified

September 9, 2026

Advisory Details (4)

Auto-updated Aug 25, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_release, github, github_pr.
github_release Patch Available

3.20.6

Patch available: versatica/mediasoup 3.20.6

https://github.com/versatica/mediasoup/releases/tag/3.20.6
github_commit Patch Available

commit 9c1a90a8f920 (versatica/mediasoup)

Patch available: versatica/mediasoup 3.20.7 (contains commit 9c1a90a8f920)

https://github.com/versatica/mediasoup/commit/9c1a90a8f9206b965e727d134846fb42df4980a7
github_pr Patch Available

SCTP: authenticate State Cookie in plain and pipe transports

Patch available: versatica/mediasoup 3.20.7 (PR #1829 merged 2026-06-15)

https://github.com/versatica/mediasoup/pull/1829
github Patch Available🟡 PoC Available

SCTP state cookie lacks cryptographic authentication, enabling unauthorized association establishment (RFC 9260 violation) · Advisory · versatica/mediasoup · GitHub

https://github.com/versatica/mediasoup/security/advisories/GHSA-p7x2-g5cq-fhmq

Vendor Advisories for CVE-2026-55663(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(2 across 2 ecosystems)
crates.io(1)
PackageVulnerable rangeFixed inDependents
mediasoup—0.22.5—
npm(1)
PackageVulnerable rangeFixed inDependents
mediasoup—3.20.6—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 12× in last 7d / 43× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-19 07:36 UTCEG score recompute
  2. 2026-09-18 19:28 UTCEPSS rescore
  3. 2026-09-18 08:57 UTCEG score recompute
  4. 2026-09-17 19:31 UTCEPSS rescore
  5. 2026-09-17 10:19 UTCEG score recompute
  6. 2026-09-16 14:08 UTCEPSS rescore
  7. 2026-09-16 11:41 UTCEG score recompute
  8. 2026-09-16 05:15 UTCEPSS rescore
  9. 2026-09-15 13:04 UTCEG score recompute
  10. 2026-09-15 03:11 UTCEPSS rescore
  11. 2026-09-14 14:26 UTCEG score recompute
  12. 2026-09-13 16:47 UTCEPSS rescore
  13. 2026-09-11 18:30 UTCEG score recompute
  14. 2026-09-10 19:52 UTCEG score recompute
  15. 2026-09-10 09:35 UTCEPSS rescore
  16. 2026-09-09 01:12 UTCEG score recompute
  17. 2026-09-08 22:01 UTCEPSS rescore
  18. 2026-09-08 01:38 UTCEG score recompute
  19. 2026-09-07 16:01 UTCEPSS rescore
  20. 2026-09-07 03:01 UTCEG score recompute
  21. 2026-09-06 13:47 UTCEPSS rescore
  22. 2026-09-06 04:23 UTCEG score recompute
  23. 2026-09-05 05:46 UTCEG score recompute
  24. 2026-09-04 07:08 UTCEG score recompute
  25. 2026-09-04 05:06 UTCEPSS rescore
Show 18 more
  1. 2026-09-03 08:04 UTCEG score recompute
  2. 2026-09-02 14:12 UTCEPSS rescore
  3. 2026-09-02 09:23 UTCEG score recompute
  4. 2026-09-01 13:54 UTCEPSS rescore
  5. 2026-08-31 12:07 UTCEG score recompute
  6. 2026-08-30 19:17 UTCEPSS rescore
  7. 2026-08-30 13:29 UTCEG score recompute
  8. 2026-08-30 01:22 UTCEPSS rescore
  9. 2026-08-29 14:51 UTCEG score recompute
  10. 2026-08-28 21:41 UTCEPSS rescore
  11. 2026-08-27 16:37 UTCEG score recompute
  12. 2026-08-27 14:25 UTCEPSS rescore
  13. 2026-08-26 17:58 UTCEG score recompute
  14. 2026-08-26 14:46 UTCEPSS rescore
  15. 2026-08-25 19:20 UTCEG score recompute
  16. 2026-08-25 19:10 UTCEG score recompute
  17. 2026-08-25 18:30 UTCEG score recompute
  18. 2026-08-25 18:29 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-55663?
CVE-2026-55663 is a medium vulnerability published on August 25, 2026. mediasoup is a WebRTC video conferencing system. From version 3.20.0 until 3.20.6 for the npm package and from 0.22.0 until 0.22.5 for the Rust crate, mediasoup's built-in SCTP stack authenticates state cookies using only the hardcoded msworker and 0xAD81 magic values instead of a per-instance…
When was CVE-2026-55663 disclosed?
CVE-2026-55663 was first published in the National Vulnerability Database on August 25, 2026, with the most recent update on September 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55663 actively exploited?
CVE-2026-55663 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 95.1% of all scored CVEs.
What is the CVSS score of CVE-2026-55663?
CVE-2026-55663 has a CVSS v3 base score of 5.6 (NVD).
How do I remediate CVE-2026-55663?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55663, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-55663

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