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: 0.6% (48th 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
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 7.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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
7.5HIGHmedium confidence
EG Risk
49
EG Risk 49/100CISA 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
Severity75% × 45%
Exploitation1% × 40%
Automatability100% × 15%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.6%
EPSS %ILE
48th
KEV
Not listed

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

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (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 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
githubMentions a patch (unverified)

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 rangeFix by version rangeDependents
org.http4s:http4s-blaze-server_2.120.10.0-M10 ... 0.23.9 (241 versions)
  • every version up to 0.23.18: fixed in 0.23.18
—
org.http4s:http4s-blaze-server_2.131.0.0-M10 ... 1.0.0-M9 (38 versions)
  • every version up to 0.23.18: fixed in 0.23.18
  • 1.0.0-M1 up to 1.0.0-M42: fixed in 1.0.0-M42
—
org.http4s:http4s-blaze-server_31.0.0-M22 ... 1.0.0-M41 (19 versions)
  • 1.0.0-M1 up to 1.0.0-M42: fixed in 1.0.0-M42
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 10× in last 7d / 47× 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 104 total refreshes for this CVE.

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Related CVEs(same product + same CWE)

Same product

2 shown

Maven:org.http4s:http4s-blaze-server_2.12 · Maven:org.http4s:http4s-blaze-server_2.13

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 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 0.6% probability of exploitation in the next 30 days (48th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-73493?
CVE-2026-73493 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-2026-73493?
A fix for CVE-2026-73493 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-73493 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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