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% (7th percentile of EPSS-scored CVEs). 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: 0.2%CVSS: 5.6Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

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
5.6MEDIUMmedium confidence
EG Risk
41
EG Risk 41/100CISA SSVC

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%
CISA SSVC: Track at low or medium mission impact; Track* at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.2%
EPSS %ILE
7th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

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
githubMentions a patch (unverified)🟡 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 rangeFix by version rangeDependents
mediasoup—
  • 0.22.0 up to 0.22.5: fixed in 0.22.5
—
npm(1)
PackageVulnerable rangeFix by version rangeDependents
mediasoup—
  • 3.20.0 up to 3.20.6: fixed in 3.20.6
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 51× 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. 2026-10-10 20:00 UTCEPSS rescore
  2. 2026-10-10 11:45 UTCEG score recompute
  3. 2026-10-09 20:07 UTCEPSS rescore
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  25. 2026-09-28 13:51 UTCEPSS rescore
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  1. 2026-09-27 20:37 UTCEG score recompute
  2. 2026-09-27 13:48 UTCEPSS rescore
  3. 2026-09-26 21:59 UTCEG score recompute
  4. 2026-09-26 15:59 UTCEPSS rescore
  5. 2026-09-25 00:22 UTCEG score recompute
  6. 2026-09-24 14:04 UTCEPSS rescore
  7. 2026-09-24 01:29 UTCEG score recompute
  8. 2026-09-23 17:54 UTCEPSS rescore
  9. 2026-09-23 02:52 UTCEG score recompute
  10. 2026-09-22 04:14 UTCEG score recompute
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  12. 2026-09-20 20:16 UTCEPSS rescore
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  15. 2026-09-18 19:28 UTCEPSS rescore
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  18. 2026-09-17 10:19 UTCEG score recompute
  19. 2026-09-16 14:08 UTCEPSS rescore
  20. 2026-09-16 11:41 UTCEG score recompute
  21. 2026-09-16 05:15 UTCEPSS rescore
  22. 2026-09-15 13:04 UTCEG score recompute
  23. 2026-09-15 03:11 UTCEPSS rescore
  24. 2026-09-14 14:26 UTCEG score recompute
  25. 2026-09-13 16:47 UTCEPSS rescore
  26. 2026-09-11 18:30 UTCEG score recompute
  27. 2026-09-10 19:52 UTCEG score recompute
  28. 2026-09-10 09:35 UTCEPSS rescore
  29. 2026-09-09 01:12 UTCEG score recompute
  30. 2026-09-08 22:01 UTCEPSS rescore
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  32. 2026-09-07 16:01 UTCEPSS rescore
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  34. 2026-09-06 13:47 UTCEPSS rescore
  35. 2026-09-06 04:23 UTCEG score recompute
  36. 2026-09-05 05:46 UTCEG score recompute
  37. 2026-09-04 07:08 UTCEG score recompute
  38. 2026-09-04 05:06 UTCEPSS rescore
  39. 2026-09-03 08:04 UTCEG score recompute
  40. 2026-09-02 14:12 UTCEPSS rescore
  41. 2026-09-02 09:23 UTCEG score recompute
  42. 2026-09-01 13:54 UTCEPSS rescore
  43. 2026-08-31 12:07 UTCEG score recompute
  44. 2026-08-30 19:17 UTCEPSS rescore
  45. 2026-08-30 13:29 UTCEG score recompute
  46. 2026-08-30 01:22 UTCEPSS rescore
  47. 2026-08-29 14:51 UTCEG score recompute
  48. 2026-08-28 21:41 UTCEPSS rescore
  49. 2026-08-27 16:37 UTCEG score recompute
  50. 2026-08-27 14:25 UTCEPSS rescore
  51. 2026-08-26 17:58 UTCEG score recompute
  52. 2026-08-26 14:46 UTCEPSS rescore
  53. 2026-08-25 19:20 UTCEG score recompute
  54. 2026-08-25 19:10 UTCEG score recompute
  55. 2026-08-25 18:30 UTCEG score recompute
  56. 2026-08-25 18:29 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

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 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 0.2% probability of exploitation in the next 30 days (7th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-55663?
CVE-2026-55663 has a CVSS base score of 5.6 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-55663?
A fix for CVE-2026-55663 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-55663 are linked in the Vendor Advisories panel on this page.

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