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CVE-2026-73494

blaze: Multiple HTTP/1.1 request-smuggling primitives in blaze's Java wire parser

CVSS score

7.4

EPSS probability

%0.6

Risk score

0.0

Published

1 mo ago

Official patch verified

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Vulnerability description

DayBreach CVE AI Research

CVE-2026-73494 has vendor, distribution, patch and security-source records on file. We can compare them and prepare an explanation linked to the evidence.

blaze is a Scala library for building asynchronous pipelines, with a focus on network IO. Prior to 0.23.18 and from 1.0.0-M1 until 1.0.0-M42, five HTTP/1.1 conformance laxities in the hand-written Java parser under http/src/main/java/org/http4s/blaze/http/parser/ can cause blaze to derive a different request boundary than a stricter fronting intermediary. A default BlazeServerBuilder accepts invalid or valueless header field names that violate tchar syntax, obsolete folded field lines (obs-fold), unsupported Transfer-Encoding values, duplicate Content-Length fields, and requests containing both Transfer-Encoding and Content-Length. If a lenient or legacy proxy forwards the malformed bytes but interprets them differently, the disagreement can permit front-end authorization bypass, response-queue poisoning on pooled backend connections, or cache poisoning. Exploitation requires a pair of disagreeing parsers; no non-default blaze configuration is required. The affected checks are enforced in BodyAndHeaderParser and Http1ServerParser. This issue is fixed in versions 0.23.18 and 1.0.0-M42.

IMPACT: Affected Products and Software

Affected Products

The following products are affected by CVE-2026-73494 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.

IDVENDORPRODUCTACTION
1http4sblaze View
2org.http4sblaze-http_2.13 View
3org.http4sblaze-http_3 View
4org.http4shttp4s-blaze-server_2.13 View
5mavenorg.http4s:http4s-blaze-server_2.13 View
6mavenorg.http4s:blaze-http_2.13 View
7mavenorg.http4s:blaze-http_3 View
8mavenorg.http4s:blaze-http_3 View
9mavenorg.http4s:blaze-http_2.13 View
10mavenorg.http4s:http4s-blaze-server_2.13 View
11mavenorg.http4s:blaze-http_2.13 View
12mavenorg.http4s:blaze-http_3 View
13mavenorg.http4s:blaze-http_3 View
14mavenorg.http4s:blaze-http_2.13 View
Total affected vendors: 3|Products: 14

RED HAT CSAF/VEX: Product Impact Check

Red Hat has not yet published a CSAF/VEX impact record for this CVE. This does not mean “not affected”.

SCORING: CVSS from Multiple Sources

CVSS Scores

The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.

SCOREVERSIONSEVERITYVECTORSOURCE
7.4CVSS 3.x—Vector not publishedGitHub Advisory
7.4CVSS V31HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:NNVD
7.4CVSS V3_1HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:NCVE CNA
0.0CVSS 4.0—Vector not publishedGitHub Advisory

Patch and Remediation Guide

Solution & Remediation Advisory

Patch verified

5 doğrulanmış yama veya düzeltilmiş sürüm kanıtı bulundu.

osvorg.http4s:http4s-blaze-server_2.130.23.18

OSV düzeltilmiş sürüm: 0.23.18

osvorg.http4s:blaze-http_2.130.23.18

OSV düzeltilmiş sürüm: 0.23.18

osvorg.http4s:blaze-http_30.23.18

OSV düzeltilmiş sürüm: 0.23.18

osvorg.http4s:blaze-http_31.0.0-M42

OSV düzeltilmiş sürüm: 1.0.0-M42

osvorg.http4s:blaze-http_2.131.0.0-M42

OSV düzeltilmiş sürüm: 1.0.0-M42

Confirm the affected product and version against the source evidence above.
Restrict access to internet-facing services and apply network segmentation.
Apply the official update named in the evidence only to the matching product and version.
Monitor server logs and network endpoints for signs of anomalous execution.

Public exploit and active exploitation status

Verified exploit intelligence

No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.

Weakness Classification and Attack Patterns (CWE & CAPEC)

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-73494 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-73494 weaknesses.

Attack Vector and Accessibility

ExposureAğ üzerinden
PermissionsGerekmiyor
UserGerekmiyor

Official Sources and Advisories

CVSS Vector Radar Chart

7.4 / 10
Attack VectorNetworkComplexityHighPrivilegesNoneUser Interact.NoneConfidentialityHighIntegrityNoneAvailabilityNone

Vulnerability Scoring Details

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack VectorNetwork
Attack ComplexityHigh
Privileges RequiredNone required
User InteractionNone required
Confidentiality (Gizlilik)High
Integrity (Bütünlük)None
Availability (Erişilebilirlik)None

Yama doğrulandı

5 doğrulanmış yama veya düzeltilmiş sürüm kanıtı bulundu.

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Weakness Type (CWE & CAPEC)

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