CVE-2026-27889

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.6%, top 55% 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
Trending — 3 sources updated this weekElevated
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 7.5Exploit: Elevated riskExposed: 0

A fix is available — apply it.

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Starting in version 2.2.0 and prior to versions 2.11.14 and 2.12.5, a missing sanity check on a WebSockets frame could trigger a server panic in the nats-server. This happens before authentication, and so is exposed to anyone who can connect to the websockets port. Versions 2.11.14 and 2.12.5 contains a fix. A workaround is available. The vulnerability only affects deployments which use WebSockets and which expose the network port to untrusted end-points. If one is able to do so, a defense in depth of restricting either of these will mitigate the attack.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
65(Attend)
EG Risk 65/100SSVC: Attend

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
Severity75% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
1%
EPSS %ILE
45%
KEV
Not listed

Published

March 25, 2026

Last Modified

August 24, 2026

Advisory Details (8)

Auto-updated Jul 3, 2026
🔬 Proof of concept available. Patch available. Sources: github, redhat.
redhat Patch Available
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27889.json
redhat

2451447 – (CVE-2026-27889) CVE-2026-27889 github.com/nats-io/nats-server: NATS-Server: Denial of Service via malformed WebSockets frame

https://bugzilla.redhat.com/show_bug.cgi?id=2451447
redhat Patch Available

cve-details

https://access.redhat.com/security/cve/CVE-2026-27889
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:23345
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:22347
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:21769
github Patch Available🟡 PoC Available

Pre-auth remote server crash via WebSocket frame length overflow in wsRead · Advisory · nats-io/nats-server · GitHub

https://github.com/nats-io/nats-server/security/advisories/GHSA-pq2q-rcw4-3hr6
generic
https://advisories.nats.io/CVE/secnote-2026-03.txt

Vendor Advisories for CVE-2026-27889(3)

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

Patch Availability(3)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatmulticluster-globalhub/multicluster-globalhub-grafana-rhel9:17801671182026-06-04redhat
redhatmulticluster-globalhub/multicluster-globalhub-grafana-rhel9:17795794392026-06-01redhat
redhatmulticluster-globalhub/multicluster-globalhub-grafana-rhel9:17788677532026-05-28redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(5 across 4 ecosystems)
Go(2)
PackageVulnerable rangeFixed inDependents
github.com/nats-io/nats-server———
github.com/nats-io/nats-server/v2—2.12.5—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
nats-server2.10.1-1 ... 2.9.19-1 (14 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
nats-server2.10.27-1, 2.12.4-1, 2.12.6-1, 2.14.1-1, 2.14.3-1——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
nats-server2.10.27-1, 2.12.4-12.12.6-1—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 76× 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.

Showing the most recent 100 of 124 total refreshes for this CVE.

  1. 2026-08-25 13:48 UTCEPSS rescore
  2. 2026-08-24 13:31 UTCEG score recompute
  3. 2026-08-24 13:31 UTCVendor advisory
  4. 2026-08-24 12:27 UTCEG score recompute
  5. 2026-08-24 12:27 UTCVendor advisory
  6. 2026-08-23 00:19 UTCEPSS rescore
  7. 2026-08-21 23:49 UTCEPSS rescore
  8. 2026-08-20 22:55 UTCEPSS rescore
  9. 2026-08-19 17:03 UTCEPSS rescore
  10. 2026-08-18 13:48 UTCEPSS rescore
  11. 2026-08-17 13:47 UTCEPSS rescore
  12. 2026-08-17 12:21 UTCEG score recompute
  13. 2026-08-17 12:21 UTCVendor advisory
  14. 2026-08-17 12:13 UTCEG score recompute
  15. 2026-08-17 12:13 UTCVendor advisory
  16. 2026-08-16 14:56 UTCEPSS rescore
  17. 2026-08-16 10:13 UTCEG score recompute
  18. 2026-08-16 10:13 UTCVendor advisory
  19. 2026-08-16 02:14 UTCEPSS rescore
  20. 2026-08-15 01:30 UTCEPSS rescore
  21. 2026-08-15 00:42 UTCVendor advisory
  22. 2026-08-14 13:28 UTCEG score recompute
  23. 2026-08-14 13:28 UTCVendor advisory
  24. 2026-08-14 12:30 UTCEG score recompute
  25. 2026-08-14 12:30 UTCVendor advisory
Show 75 more
  1. 2026-08-14 06:31 UTCEG score recompute
  2. 2026-08-14 06:31 UTCVendor advisory
  3. 2026-08-13 22:00 UTCEPSS rescore
  4. 2026-08-12 20:48 UTCEG score recompute
  5. 2026-08-12 20:48 UTCVendor advisory
  6. 2026-08-12 13:50 UTCEPSS rescore
  7. 2026-08-11 20:52 UTCEG score recompute
  8. 2026-08-11 20:52 UTCVendor advisory
  9. 2026-08-11 13:42 UTCEPSS rescore
  10. 2026-08-11 03:56 UTCEG score recompute
  11. 2026-08-11 03:56 UTCVendor advisory
  12. 2026-08-11 00:00 UTCEPSS rescore
  13. 2026-08-10 13:22 UTCEG score recompute
  14. 2026-08-10 13:22 UTCVendor advisory
  15. 2026-08-10 12:27 UTCEG score recompute
  16. 2026-08-10 12:27 UTCVendor advisory
  17. 2026-08-10 04:35 UTCVendor advisory
  18. 2026-08-09 17:20 UTCEG score recompute
  19. 2026-08-09 17:20 UTCVendor advisory
  20. 2026-08-09 13:46 UTCEPSS rescore
  21. 2026-08-09 06:07 UTCEG score recompute
  22. 2026-08-09 06:07 UTCVendor advisory
  23. 2026-08-08 16:37 UTCEPSS rescore
  24. 2026-08-08 03:40 UTCEG score recompute
  25. 2026-08-08 03:40 UTCVendor advisory
  26. 2026-08-07 16:27 UTCVendor advisory
  27. 2026-08-06 18:50 UTCEG score recompute
  28. 2026-08-06 18:50 UTCVendor advisory
  29. 2026-08-06 13:46 UTCEPSS rescore
  30. 2026-08-06 00:57 UTCEG score recompute
  31. 2026-08-06 00:57 UTCVendor advisory
  32. 2026-08-05 19:17 UTCEPSS rescore
  33. 2026-08-04 15:10 UTCEPSS rescore
  34. 2026-08-04 00:58 UTCVendor advisory
  35. 2026-08-03 13:44 UTCEG score recompute
  36. 2026-08-03 13:44 UTCVendor advisory
  37. 2026-08-03 12:49 UTCEG score recompute
  38. 2026-08-03 12:49 UTCVendor advisory
  39. 2026-08-03 10:36 UTCEPSS rescore
  40. 2026-08-03 02:41 UTCVendor advisory
  41. 2026-08-02 15:27 UTCEG score recompute
  42. 2026-08-02 15:27 UTCVendor advisory
  43. 2026-08-02 02:26 UTCEPSS rescore
  44. 2026-08-01 04:16 UTCEPSS rescore
  45. 2026-07-30 16:27 UTCEPSS rescore
  46. 2026-07-30 01:30 UTCEPSS rescore
  47. 2026-07-28 15:36 UTCEPSS rescore
  48. 2026-07-27 13:31 UTCEG score recompute
  49. 2026-07-27 13:31 UTCVendor advisory
  50. 2026-07-27 12:41 UTCEG score recompute
  51. 2026-07-27 12:41 UTCVendor advisory
  52. 2026-07-26 14:54 UTCEPSS rescore
  53. 2026-07-26 14:54 UTCEPSS rescore
  54. 2026-07-25 14:18 UTCEPSS rescore
  55. 2026-07-25 14:17 UTCEPSS rescore
  56. 2026-07-24 14:17 UTCEPSS rescore
  57. 2026-07-23 14:18 UTCEPSS rescore
  58. 2026-07-23 14:18 UTCEPSS rescore
  59. 2026-07-23 03:08 UTCEG score recompute
  60. 2026-07-22 14:08 UTCEPSS rescore
  61. 2026-07-22 14:08 UTCEPSS rescore
  62. 2026-07-21 15:24 UTCEPSS rescore
  63. 2026-07-21 15:24 UTCEPSS rescore
  64. 2026-07-20 17:08 UTCEPSS rescore
  65. 2026-07-20 17:08 UTCEPSS rescore
  66. 2026-07-19 14:31 UTCEPSS rescore
  67. 2026-07-19 14:31 UTCEPSS rescore
  68. 2026-07-19 02:29 UTCEPSS rescore
  69. 2026-07-18 10:04 UTCEPSS rescore
  70. 2026-07-18 10:04 UTCEPSS rescore
  71. 2026-07-18 06:59 UTCOSV refresh
  72. 2026-07-16 17:03 UTCEPSS rescore
  73. 2026-07-16 17:03 UTCEPSS rescore
  74. 2026-07-15 16:57 UTCEPSS rescore
  75. 2026-07-15 16:57 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-27889?
CVE-2026-27889 is a high vulnerability published on March 25, 2026. NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Starting in version 2.2.0 and prior to versions 2.11.14 and 2.12.5, a missing sanity check on a WebSockets frame could trigger a server panic in the nats-server. This happens before authentication, and…
When was CVE-2026-27889 disclosed?
CVE-2026-27889 was first published in the National Vulnerability Database on March 25, 2026, with the most recent update on August 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-27889 actively exploited?
CVE-2026-27889 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 54.8% of all scored CVEs.
What is the CVSS score of CVE-2026-27889?
CVE-2026-27889 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-27889?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-27889, 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

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