GHSA-7ppr-r889-mcf2

Suggest an improvement
Source
https://github.com/advisories/GHSA-7ppr-r889-mcf2
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-7ppr-r889-mcf2/GHSA-7ppr-r889-mcf2.json
JSON Data
https://api.osv.dev/v1/vulns/GHSA-7ppr-r889-mcf2
Published
2026-07-24T22:28:05Z
Modified
2026-07-24T22:45:39.237235677Z
Severity
  • 7.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
Summary
blaze: Unbounded WebSocket message aggregation in http4s-blaze-server
Details

Summary

http4s-blaze-server aggregates the 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 via OutOfMemoryError.

Impact

Any http4s application serving WebSocket routes over BlazeServerBuilder is affected; no non-default configuration is required, and maxWebSocketBufferSize does not bound the aggregate (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. Where the WebSocket endpoint is reachable without authentication the attacker is unauthenticated and remote; where the handshake requires a principal, any authenticated client can still trigger it.

Workarounds

  • No blaze-server configuration bounds the aggregate; maxWebSocketBufferSize is not a mitigation.
  • Terminate/limit WebSocket traffic at a fronting layer that enforces message-size and fragment limits, or disable WebSocket routes.
  • Longer term: blaze is EOL upstream; plan migration to a maintained backend (e.g. ember).
Database specific 
{
    "nvd_published_at": null,
    "severity": "HIGH",
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-24T22:28:05Z",
    "cwe_ids": [
        "CWE-770"
    ]
}
References

Affected packages

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

Package

Name
org.http4s:http4s-blaze-server_2.13
View open source insights on deps.dev
Purl
pkg:maven/org.http4s/http4s-blaze-server_2.13

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
0.23.18

Affected versions

0.*
0.10.0-M10
0.21.0-M1
0.21.0-M2
0.21.0-M3
0.21.0-M4
0.21.0-M5
0.21.0-M6
0.21.0-RC1
0.21.0-RC2
0.21.0-RC3
0.21.0-RC4
0.21.0-RC5
0.21.0
0.21.1
0.21.2
0.21.3
0.21.4
0.21.5
0.21.6
0.21.7
0.21.8
0.21.9
0.21.11
0.21.12
0.21.13
0.21.14
0.21.15
0.21.16
0.21.17
0.21.18
0.21.19
0.21.20
0.21.21
0.21.22
0.21.23
0.21.24
0.21.25
0.21.26
0.21.27
0.21.28
0.21.29
0.21.30
0.21.31
0.21.32
0.21.33
0.21.34
0.22.0-M1
0.22.0-M2
0.22.0-M3
0.22.0-M4
0.22.0-M5
0.22.0-M6
0.22.0-M7
0.22.0-M8
0.22.0-RC1
0.22.0
0.22-53-01128f5
0.22-96-55d3184
0.22-129-24d065b
0.22-143-49b5a8d
0.22.1
0.22.2
0.22.3
0.22.4
0.22.5
0.22.6
0.22.7
0.22.8
0.22.9
0.22.10
0.22.11
0.22.12
0.22.13
0.22.14
0.22.15
0.23.0-M1
0.23.0-RC1
0.23.0
0.23.1
0.23.2
0.23.3
0.23.4
0.23.5
0.23.6
0.23.7
0.23.8
0.23.9
0.23.10
0.23.11
0.23.12
0.23.13
0.23.14
0.23.15
0.23.16
0.23.17

Database specific

source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-7ppr-r889-mcf2/GHSA-7ppr-r889-mcf2.json"
org.http4s:http4s-blaze-server_2.13

Package

Name
org.http4s:http4s-blaze-server_2.13
View open source insights on deps.dev
Purl
pkg:maven/org.http4s/http4s-blaze-server_2.13

Affected ranges

Type
ECOSYSTEM
Events
Introduced
1.0.0-M1
Fixed
1.0.0-M42

Affected versions

1.*
1.0.0-M2
1.0.0-M3
1.0.0-M4
1.0.0-M5
1.0.0-M6
1.0.0-M7
1.0.0-M8
1.0.0-M9
1.0.0-M10
1.0.0-M11
1.0.0-M13
1.0.0-M14
1.0.0-M15
1.0.0-M16
1.0.0-M17
1.0.0-M18
1.0.0-M19
1.0.0-M20
1.0.0-M21
1.0.0-M22
1.0.0-M23
1.0.0-M24
1.0.0-M25
1.0.0-M27
1.0.0-M28
1.0.0-M29
1.0.0-M30
1.0.0-M31
1.0.0-M32
1.0.0-M33
1.0.0-M34
1.0.0-M35
1.0.0-M36
1.0.0-M37
1.0.0-M38
1.0.0-M39
1.0.0-M40
1.0.0-M41

Database specific

source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-7ppr-r889-mcf2/GHSA-7ppr-r889-mcf2.json"
org.http4s:http4s-blaze-server_2.12

Package

Name
org.http4s:http4s-blaze-server_2.12
View open source insights on deps.dev
Purl
pkg:maven/org.http4s/http4s-blaze-server_2.12

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
0.23.18

Affected versions

0.*
0.10.0-M10
0.15.0
0.15.0a
0.15.1
0.15.1a
0.15.2
0.15.2a
0.15.3
0.15.3a
0.15.4
0.15.4a
0.15.5
0.15.5a
0.15.6
0.15.6a
0.15.7
0.15.7a
0.15.8
0.15.8a
0.15.9
0.15.9a
0.15.10
0.15.10a
0.15.11
0.15.11a
0.15.12
0.15.12a
0.15.13
0.15.13a
0.15.14
0.15.14a
0.15.15
0.15.15a
0.15.16
0.15.16a
0.16.0-M1
0.16.0-M2
0.16.0-M3
0.16.0-RC1
0.16.0-RC2
0.16.0-RC3
0.16.0
0.16.0a-M1
0.16.0a-M2
0.16.0a-M3
0.16.0a-RC1
0.16.0a-RC2
0.16.0a-RC3
0.16.0a
0.16.1
0.16.1a
0.16.2
0.16.2a
0.16.3
0.16.3a
0.16.4
0.16.4a
0.16.5
0.16.5a
0.16.6
0.16.6a
0.17.0-M1
0.17.0-M2
0.17.0-M3
0.17.0-RC1
0.17.0-RC2
0.17.0-RC3
0.17.0
0.17.1
0.17.2
0.17.3
0.17.4
0.17.5
0.17.6
0.18.0-M1
0.18.0-M2
0.18.0-M3
0.18.0-M4
0.18.0-M5
0.18.0-M6
0.18.0-M7
0.18.0-M8
0.18.0-M9
0.18.0
0.18.1
0.18.2
0.18.3
0.18.4
0.18.5
0.18.6
0.18.7
0.18.8
0.18.9
0.18.10
0.18.11
0.18.12
0.18.13
0.18.14
0.18.15
0.18.16
0.18.17
0.18.18
0.18.19
0.18.20
0.18.21
0.18.22
0.18.23
0.18.24
0.18.25
0.18.26
0.19.0-M1
0.19.0-M2
0.19.0-M3
0.19.0-M4
0.19.0
0.20.0-M1
0.20.0-M2
0.20.0-M3
0.20.0-M4
0.20.0-M5
0.20.0-M6
0.20.0-M7
0.20.0-RC1
0.20.0
0.20.1
0.20.2
0.20.3
0.20.4
0.20.5
0.20.6
0.20.7
0.20.8
0.20.9
0.20.10
0.20.11
0.20.12
0.20.13
0.20.14
0.20.15
0.20.16
0.20.17
0.20.18
0.20.19
0.20.20
0.20.21
0.20.22
0.20.23
0.21.0-M1
0.21.0-M2
0.21.0-M3
0.21.0-M4
0.21.0-M5
0.21.0-M6
0.21.0-RC1
0.21.0-RC2
0.21.0-RC3
0.21.0-RC4
0.21.0-RC5
0.21.0
0.21.1
0.21.2
0.21.3
0.21.4
0.21.5
0.21.6
0.21.7
0.21.8
0.21.9
0.21.11
0.21.12
0.21.13
0.21.14
0.21.15
0.21.16
0.21.17
0.21.18
0.21.19
0.21.20
0.21.21
0.21.22
0.21.23
0.21.24
0.21.25
0.21.26
0.21.27
0.21.28
0.21.29
0.21.30
0.21.31
0.21.32
0.21.33
0.21.34
0.22.0-M1
0.22.0-M2
0.22.0-M3
0.22.0-M4
0.22.0-M5
0.22.0-M6
0.22.0-M7
0.22.0-M8
0.22.0-RC1
0.22.0
0.22-53-01128f5
0.22-96-55d3184
0.22-129-24d065b
0.22-143-49b5a8d
0.22.1
0.22.2
0.22.3
0.22.4
0.22.5
0.22.6
0.22.7
0.22.8
0.22.9
0.22.10
0.22.11
0.22.12
0.22.13
0.22.14
0.22.15
0.23.0-M1
0.23.0-RC1
0.23.0
0.23.1
0.23.2
0.23.3
0.23.4
0.23.5
0.23.6
0.23.7
0.23.8
0.23.9
0.23.10
0.23.11
0.23.12
0.23.13
0.23.14
0.23.15
0.23.16
0.23.17

Database specific

source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-7ppr-r889-mcf2/GHSA-7ppr-r889-mcf2.json"
org.http4s:http4s-blaze-server_3

Package

Name
org.http4s:http4s-blaze-server_3
View open source insights on deps.dev
Purl
pkg:maven/org.http4s/http4s-blaze-server_3

Affected ranges

Type
ECOSYSTEM
Events
Introduced
1.0.0-M1
Fixed
1.0.0-M42

Affected versions

1.*
1.0.0-M22
1.0.0-M23
1.0.0-M24
1.0.0-M25
1.0.0-M27
1.0.0-M28
1.0.0-M29
1.0.0-M30
1.0.0-M31
1.0.0-M32
1.0.0-M33
1.0.0-M34
1.0.0-M35
1.0.0-M36
1.0.0-M37
1.0.0-M38
1.0.0-M39
1.0.0-M40
1.0.0-M41

Database specific

source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-7ppr-r889-mcf2/GHSA-7ppr-r889-mcf2.json"