CVE-2026-73493: Http4s (http4s-blaze-server) is a minimal, idiomatic Scala interface for HTTP services

Q: How do I fix CVE-2026-73493?

No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.

Q: Is CVE-2026-73493 being exploited?

CVE-2026-73493 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-73493 affect?

CVE-2026-73493 affects affected software. Severity is high (CVSS 7.5). 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.

Q: How urgent is CVE-2026-73493?

Priority 44/100. High severity; Remotely exploitable, no login, no user action

This month

HIGH 7.5REMOTE

CVE-2026-73493 is a high-severity flaw (CVSS 7.5) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.6% (top 50%)
CISA exploited list	No
Weakness	CWE-770
Published	2026-08-12
Last modified	2026-10-24

Publisher (CNA): GitHub, Inc.

Last updated 2026-10-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Timeline

2026-08-12 22:17 UTCPublished CVE record published
2026-10-24 15:10 UTCUpdated Record last modified

Exact fixes by distribution

Maven · org.http4s:http4s-blaze-server_2.13 · FIXED · 0.23.18 · vulnerable: < 0.23.18 · source

Set org.http4s:http4s-blaze-server_2.13 to 0.23.18 or later in pom.xml or build.gradle, then rebuild and redeploy.

Maven · org.http4s:http4s-blaze-server_2.12 · FIXED · 0.23.18 · vulnerable: < 0.23.18 · source

Set org.http4s:http4s-blaze-server_2.12 to 0.23.18 or later in pom.xml or build.gradle, then rebuild and redeploy.

Maven · org.http4s:http4s-blaze-server_3 · FIXED · 1.0.0-M42 · vulnerable: >= 1.0.0-M1, < 1.0.0-M42 · source

Set org.http4s:http4s-blaze-server_3 to 1.0.0-M42 or later in pom.xml or build.gradle, then rebuild and redeploy.

Fedora 46 · fooyin · FIXED · 0.14.1-6.fc46 · FEDORA-2026-a597ed324c · source

sudo dnf upgrade --advisory=FEDORA-2026-a597ed324c

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-73493?

No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.

Is CVE-2026-73493 being exploited?

CVE-2026-73493 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-73493 affect?

CVE-2026-73493 affects affected software. Severity is high (CVSS 7.5). 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.

How urgent is CVE-2026-73493?

Priority 44/100. High severity; Remotely exploitable, no login, no user action

References

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