CVE-2026-27571

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.5%, top 61% 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, nvd
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%CVSS: 7.5Exploit: None knownExposed: 0

A fix is available — apply it.

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The WebSockets handling of NATS messages handles compressed messages via the WebSockets negotiated compression. Prior to versions 2.11.2 and 2.12.3, the implementation bound the memory size of a NATS message but did not independently bound the memory consumption of the memory stream when constructing a NATS message which might then fail validation for size reasons. An attacker can use a compression bomb to cause excessive memory consumption, often resulting in the operating system terminating the server process. The use of compression is negotiated before authentication, so this does not require valid NATS credentials to exploit. The fix, present in versions 2.11.2 and 2.12.3, was to bounds the decompression to fail once the message was too large, instead of continuing on. The vulnerability only affects deployments which use WebSockets and which expose the network port to untrusted end-points.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
34(Track)
EG Risk 34/100SSVC: 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
Severity75% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
40%
KEV
Not listed

Published

February 24, 2026

Last Modified

June 17, 2026

Advisory Details (4)

Auto-updated Aug 4, 2026
Patch available. Sources: github_commit, github_release, github.
github Patch Available

nats-server WebSockets pre-auth memory DoS · Advisory · nats-io/nats-server · GitHub

https://github.com/nats-io/nats-server/security/advisories/GHSA-qrvq-68c2-7grw
github_release Patch Available

Release v2.12.3

Patch available: nats-io/nats-server v2.12.3

https://github.com/nats-io/nats-server/releases/tag/v2.12.3
github_release Patch Available

Release v2.11.12

Patch available: nats-io/nats-server v2.11.12

https://github.com/nats-io/nats-server/releases/tag/v2.11.12
github_commit

commit f77fb7c4535e (nats-io/nats-server)

Fix landed in nats-io/nats-server commit f77fb7c4535e — awaiting tagged release

https://github.com/nats-io/nats-server/commit/f77fb7c4535e6727cc1a2899cd8e6bbdd8ba2017

Vendor Advisories for CVE-2026-27571(2)

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

Patch Availability(2)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatmulticluster-globalhub/multicluster-globalhub-grafana-rhel9:17736500602026-03-31redhat
redhatmulticluster-globalhub/multicluster-globalhub-grafana-rhel9:17736507672026-03-19redhat

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—2.12.3—
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-server2.10.27-12.12.4-1—

Weakness Classification(2)

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

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 7× in last 7d / 27× 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. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-18 19:27 UTCEPSS rescore
  3. 2026-09-17 19:30 UTCEPSS rescore
  4. 2026-09-16 14:08 UTCEPSS rescore
  5. 2026-09-16 05:15 UTCEPSS rescore
  6. 2026-09-13 16:47 UTCEPSS rescore
  7. 2026-09-12 15:01 UTCEPSS rescore
  8. 2026-09-11 14:52 UTCEPSS rescore
  9. 2026-09-10 09:34 UTCEPSS rescore
  10. 2026-09-08 22:00 UTCEPSS rescore
  11. 2026-09-07 16:01 UTCEPSS rescore
  12. 2026-09-06 13:47 UTCEPSS rescore
  13. 2026-09-06 13:47 UTCEPSS rescore
  14. 2026-09-04 05:06 UTCEPSS rescore
  15. 2026-09-02 14:11 UTCEPSS rescore
  16. 2026-09-01 13:53 UTCEPSS rescore
  17. 2026-09-01 04:39 UTCEPSS rescore
  18. 2026-08-31 18:04 UTCOSV refresh
  19. 2026-08-30 19:17 UTCEPSS rescore
  20. 2026-08-30 01:22 UTCEPSS rescore
  21. 2026-08-28 21:41 UTCEPSS rescore
  22. 2026-08-27 14:25 UTCEPSS rescore
  23. 2026-08-26 14:46 UTCEPSS rescore
  24. 2026-08-25 13:48 UTCEPSS rescore
  25. 2026-08-23 00:19 UTCEPSS rescore
Show 49 more
  1. 2026-08-21 23:49 UTCEPSS rescore
  2. 2026-08-20 22:55 UTCEPSS rescore
  3. 2026-08-19 17:03 UTCEPSS rescore
  4. 2026-08-18 13:48 UTCEPSS rescore
  5. 2026-08-17 13:47 UTCEPSS rescore
  6. 2026-08-16 14:56 UTCEPSS rescore
  7. 2026-08-16 02:14 UTCEPSS rescore
  8. 2026-08-15 01:30 UTCEPSS rescore
  9. 2026-08-14 22:24 UTCVendor advisory
  10. 2026-08-14 09:06 UTCEG score recompute
  11. 2026-08-14 09:06 UTCVendor advisory
  12. 2026-08-13 22:00 UTCEPSS rescore
  13. 2026-08-13 01:06 UTCEG score recompute
  14. 2026-08-13 01:06 UTCVendor advisory
  15. 2026-08-12 13:50 UTCEPSS rescore
  16. 2026-08-12 00:52 UTCEG score recompute
  17. 2026-08-12 00:52 UTCVendor advisory
  18. 2026-08-11 13:42 UTCEPSS rescore
  19. 2026-08-11 06:36 UTCEG score recompute
  20. 2026-08-11 06:36 UTCVendor advisory
  21. 2026-08-11 00:00 UTCEPSS rescore
  22. 2026-08-10 13:17 UTCVendor advisory
  23. 2026-08-09 21:42 UTCEG score recompute
  24. 2026-08-09 21:42 UTCVendor advisory
  25. 2026-08-09 13:46 UTCEPSS rescore
  26. 2026-08-09 08:44 UTCEG score recompute
  27. 2026-08-09 08:44 UTCVendor advisory
  28. 2026-08-08 16:37 UTCEPSS rescore
  29. 2026-08-08 09:48 UTCVendor advisory
  30. 2026-08-07 20:50 UTCEG score recompute
  31. 2026-08-07 20:50 UTCVendor advisory
  32. 2026-08-06 13:46 UTCEPSS rescore
  33. 2026-08-06 03:04 UTCEG score recompute
  34. 2026-08-06 03:04 UTCVendor advisory
  35. 2026-08-05 19:17 UTCEPSS rescore
  36. 2026-08-04 15:10 UTCEPSS rescore
  37. 2026-08-04 05:57 UTCEG score recompute
  38. 2026-08-04 05:57 UTCVendor advisory
  39. 2026-08-03 10:36 UTCEPSS rescore
  40. 2026-08-02 19:40 UTCEG score recompute▲ 1.60
  41. 2026-08-02 19:40 UTCVendor advisory
  42. 2026-08-02 02:26 UTCEPSS rescore
  43. 2026-08-01 04:16 UTCEPSS rescore
  44. 2026-07-30 16:27 UTCEPSS rescore
  45. 2026-07-30 01:30 UTCEPSS rescore
  46. 2026-07-28 15:36 UTCEPSS rescore
  47. 2026-07-27 12:55 UTCEG score recompute
  48. 2026-07-27 12:55 UTCVendor advisory
  49. 2026-07-27 12:50 UTCOSV refresh

Frequently asked(5)

What is CVE-2026-27571?
CVE-2026-27571 is a high vulnerability published on February 24, 2026. NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The WebSockets handling of NATS messages handles compressed messages via the WebSockets negotiated compression. Prior to versions 2.11.2 and 2.12.3, the implementation bound the memory size of a NATS…
When was CVE-2026-27571 disclosed?
CVE-2026-27571 was first published in the National Vulnerability Database on February 24, 2026, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-27571 actively exploited?
CVE-2026-27571 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 59.6% of all scored CVEs.
What is the CVSS score of CVE-2026-27571?
CVE-2026-27571 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-27571?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-27571, 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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