CVE-2026-73494 (GCVE-0-2026-73494)
Vulnerability from cvelistv5 – Published: 2026-09-14 17:33 – Updated: 2026-09-14 20:05
VLAI
EPSS
VEX
Title
blaze: Multiple HTTP/1.1 request-smuggling primitives in blaze's Java wire parser
Summary
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.
Severity
7.4 (High)
SSVC
Exploitation: none
Automatable: no
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-14 19:21 UTC
CWE
- CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Assigner
References
9 references
| URL | Tags |
|---|---|
| https://github.com/http4s/blaze/security/advisori… | x_refsource_CONFIRM |
| https://github.com/http4s/blaze/commit/3f7c022e30… | x_refsource_MISC |
| https://github.com/http4s/blaze/commit/4eec200780… | x_refsource_MISC |
| https://github.com/http4s/blaze/commit/927b67753a… | x_refsource_MISC |
| https://github.com/http4s/blaze/commit/a54bc9cd31… | x_refsource_MISC |
| https://github.com/http4s/blaze/commit/c47d9675f8… | x_refsource_MISC |
| https://github.com/http4s/blaze/commit/e871ebb1d2… | x_refsource_MISC |
| https://github.com/http4s/blaze/releases/tag/v0.23.18 | x_refsource_MISC |
| https://github.com/http4s/blaze/releases/tag/v1.0.0-M42 | x_refsource_MISC |
Impacted products
4 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| http4s | blaze |
Affected:
< 0.23.18
Affected: >= 1.0.0-M1, < 1.0.0-M42 |
guessed | |
| org.http4s | blaze-http_2.13 |
Affected:
< 0.23.18
Affected: >= 1.0.0-M1, < 1.0.0-M42 |
guessed | |
| org.http4s | blaze-http_3 |
Affected:
< 0.23.18
Affected: >= 1.0.0-M1, < 1.0.0-M42 |
guessed | |
| org.http4s | http4s-blaze-server_2.13 |
Affected:
< 0.23.18
|
guessed |
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},
"cveMetadata": {
"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"assignerShortName": "GitHub_M",
"cveId": "CVE-2026-73494",
"datePublished": "2026-09-14T17:33:49.671Z",
"dateReserved": "2026-08-12T19:00:33.735Z",
"dateUpdated": "2026-09-14T20:05:52.181Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
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Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.