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 54% 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
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.8%CVSS: 7.5Exploit: Elevated riskExposed services: Not assessed

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
7.5HIGHmedium confidence
EG Risk
65
EG Risk 65/100

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%
EPSS PROB
0.8%
EPSS %ILE
56th
KEV
Not listed

Published

March 25, 2026

Last Modified

September 9, 2026

Advisory Details (8)

Auto-updated Jul 3, 2026
🔬 Proof of concept available. Patch available. Sources: github, redhat.
redhatMentions a patch (unverified)
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
redhatMentions a patch (unverified)

cve-details

https://access.redhat.com/security/cve/CVE-2026-27889
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:23345
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:22347
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:21769
githubMentions a patch (unverified)🟡 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 / EcosystemFix (by version range) / 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 rangeFix by version rangeDependents
github.com/nats-io/nats-server—
  • every version on: no fix on record
—
github.com/nats-io/nats-server/v2—
  • 2.2.0 up to 2.11.14: fixed in 2.11.14
  • 2.12.0 up to 2.12.5: fixed in 2.12.5
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
nats-server2.10.1-1 ... 2.9.19-1 (15 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
nats-server2.10.27-1 ... 2.14.6-1 (6 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
nats-server2.10.27-1, 2.12.4-1
  • every version up to 2.12.6-1: fixed in 2.12.6-1
—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 6× in last 7d / 23× 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 167 total refreshes for this CVE.

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

Related CVEs(same product + 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 on March 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-2026-27889 actively exploited?
CVE-2026-27889 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.8% probability of exploitation in the next 30 days (56th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-27889?
CVE-2026-27889 has a CVSS base score of 7.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-27889?
A fix for CVE-2026-27889 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-27889 are linked in the Vendor Advisories panel on this page.

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