CVE-2026-73493

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: 0.3%, top 72% 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
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

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

Http4s (http4s-blaze-server) is a minimal, idiomatic Scala interface for HTTP services. Prior to 0.23.18 and 1.0.0-M42, http4s-blaze-server aggregates fragments of an incoming WebSocket message with no limit on total size or fragment count. A client that completes a WebSocket handshake can send an unterminated fragmented message and drive unbounded heap growth in the server JVM, resulting in denial of service through OutOfMemoryError. Any http4s application serving WebSocket routes over BlazeServerBuilder is affected, no non-default configuration is required, and maxWebSocketBufferSize does not bound the aggregate because it bounds only individual frames. A single connection sending continuation frames that never set FIN forces the server to buffer every fragment until the heap is exhausted, terminating the JVM with OutOfMemoryError on the blaze selector thread. Small fragments amplify the cost through per-frame object overhead, so a modest volume of wire bytes is sufficient. This issue is fixed in versions 0.23.18 and 1.0.0-M42.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: 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%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
28%
KEV
Not listed

Published

August 12, 2026

Last Modified

September 10, 2026

Advisory Details (4)

Auto-updated Aug 12, 2026
Patch available. Sources: github_commit, github_release, github.
github_release Patch Available

v1.0.0-M42

Patch available: http4s/blaze v1.0.0-M42 (pre-release)

https://github.com/http4s/blaze/releases/tag/v1.0.0-M42
github_release Patch Available

v0.23.18

Patch available: http4s/blaze v0.23.18

https://github.com/http4s/blaze/releases/tag/v0.23.18
github_commit Patch Available

commit 173e8ca820a0 (http4s/blaze)

Patch available: http4s/blaze v0.23.18 (contains commit 173e8ca820a0)

https://github.com/http4s/blaze/commit/173e8ca820a0d12110bfe409c72e9b9c3d28d471
github Patch Available

Unbounded WebSocket message aggregation in http4s-blaze-server · Advisory · http4s/blaze · GitHub

https://github.com/http4s/blaze/security/advisories/GHSA-7ppr-r889-mcf2

Vendor Advisories for CVE-2026-73493(1)

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

Affected Packages

(3 across 1 ecosystem)
Maven(3)
PackageVulnerable rangeFixed inDependents
org.http4s:http4s-blaze-server_2.120.10.0-M10 ... 0.23.9 (241 versions)0.23.18—
org.http4s:http4s-blaze-server_2.131.0.0-M10 ... 1.0.0-M9 (38 versions)1.0.0-M42—
org.http4s:http4s-blaze-server_31.0.0-M22 ... 1.0.0-M41 (19 versions)1.0.0-M42—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 50× 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. 2026-09-21 00:15 UTCEG score recompute
  2. 2026-09-20 20:16 UTCEPSS rescore
  3. 2026-09-19 19:43 UTCEG score recompute
  4. 2026-09-19 05:58 UTCEG score recompute
  5. 2026-09-18 19:28 UTCEPSS rescore
  6. 2026-09-18 02:42 UTCEG score recompute
  7. 2026-09-17 00:15 UTCEG score recompute
  8. 2026-09-16 14:08 UTCEPSS rescore
  9. 2026-09-16 10:48 UTCEG score recompute
  10. 2026-09-16 05:15 UTCEPSS rescore
  11. 2026-09-15 06:23 UTCEG score recompute
  12. 2026-09-15 03:12 UTCEPSS rescore
  13. 2026-09-14 03:58 UTCEG score recompute
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  15. 2026-09-12 15:02 UTCEPSS rescore
  16. 2026-09-11 23:56 UTCEG score recompute
  17. 2026-09-11 14:53 UTCEPSS rescore
  18. 2026-09-10 20:08 UTCEG score recompute
  19. 2026-09-10 09:35 UTCEPSS rescore
  20. 2026-09-09 05:10 UTCEG score recompute
  21. 2026-09-08 22:01 UTCEPSS rescore
  22. 2026-09-07 16:40 UTCEG score recompute
  23. 2026-09-06 18:39 UTCEG score recompute
  24. 2026-09-06 13:48 UTCEPSS rescore
  25. 2026-09-05 16:40 UTCEG score recompute
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  1. 2026-09-04 14:40 UTCEG score recompute
  2. 2026-09-04 05:07 UTCEPSS rescore
  3. 2026-09-02 23:25 UTCEG score recompute
  4. 2026-09-02 14:12 UTCEPSS rescore
  5. 2026-09-01 15:15 UTCEG score recompute
  6. 2026-09-01 13:54 UTCEPSS rescore
  7. 2026-09-01 04:40 UTCEPSS rescore
  8. 2026-09-01 04:40 UTCEPSS rescore
  9. 2026-08-30 23:27 UTCEG score recompute
  10. 2026-08-30 19:18 UTCEPSS rescore
  11. 2026-08-30 19:17 UTCEPSS rescore
  12. 2026-08-30 10:28 UTCEG score recompute
  13. 2026-08-30 01:22 UTCEPSS rescore
  14. 2026-08-29 08:29 UTCEG score recompute
  15. 2026-08-28 21:42 UTCEPSS rescore
  16. 2026-08-27 21:39 UTCEG score recompute
  17. 2026-08-27 14:25 UTCEPSS rescore
  18. 2026-08-26 19:36 UTCEG score recompute
  19. 2026-08-26 14:47 UTCEPSS rescore
  20. 2026-08-25 17:28 UTCEG score recompute
  21. 2026-08-25 13:49 UTCEPSS rescore
  22. 2026-08-24 15:26 UTCEG score recompute
  23. 2026-08-23 00:27 UTCEG score recompute
  24. 2026-08-23 00:19 UTCEPSS rescore
  25. 2026-08-22 11:28 UTCEG score recompute
  26. 2026-08-21 23:49 UTCEPSS rescore
  27. 2026-08-21 09:30 UTCEG score recompute
  28. 2026-08-20 22:56 UTCEPSS rescore
  29. 2026-08-19 18:33 UTCEG score recompute
  30. 2026-08-19 17:04 UTCEPSS rescore
  31. 2026-08-18 15:36 UTCEG score recompute
  32. 2026-08-18 13:49 UTCEPSS rescore
  33. 2026-08-18 13:49 UTCEPSS rescore
  34. 2026-08-18 02:22 UTCEG score recompute
  35. 2026-08-17 13:47 UTCEPSS rescore
  36. 2026-08-17 00:14 UTCEG score recompute
  37. 2026-08-16 14:56 UTCEPSS rescore
  38. 2026-08-16 14:56 UTCEPSS rescore
  39. 2026-08-16 11:14 UTCEG score recompute
  40. 2026-08-16 02:15 UTCEPSS rescore
  41. 2026-08-15 09:17 UTCEG score recompute
  42. 2026-08-15 01:31 UTCEPSS rescore
  43. 2026-08-14 07:18 UTCEG score recompute
  44. 2026-08-13 22:00 UTCEPSS rescore
  45. 2026-08-13 18:19 UTCEG score recompute
  46. 2026-08-13 18:12 UTCEG score recompute
  47. 2026-08-12 22:21 UTCEG score recompute
  48. 2026-08-12 21:21 UTCEG score recompute
  49. 2026-08-12 21:20 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-73493?
CVE-2026-73493 is a high vulnerability published on August 12, 2026. Http4s (http4s-blaze-server) is a minimal, idiomatic Scala interface for HTTP services. Prior to 0.23.18 and 1.0.0-M42, http4s-blaze-server aggregates fragments of an incoming WebSocket message with no limit on total size or fragment count. A client that completes a WebSocket handshake can send an…
When was CVE-2026-73493 disclosed?
CVE-2026-73493 was first published in the National Vulnerability Database on August 12, 2026, with the most recent update on September 10, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-73493 actively exploited?
CVE-2026-73493 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 71.8% of all scored CVEs.
What is the CVSS score of CVE-2026-73493?
CVE-2026-73493 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-73493?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-73493, 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-2026-73493

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