CVE-2026-73495

HIGHPre-NVD 7.47.4—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.4 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5% (39th 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
7.4EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 7.4Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

blaze is a Scala library for building asynchronous pipelines, with a focus on network IO. Prior to 0.23.18 and 1.0.0-M42, blaze-server can merge HTTP/1.1 chunked-body trailer fields into Request.headers. Because trailer fields are attacker-controlled, an unauthenticated remote client can inject arbitrary header names and values, including X-Forwarded-For and internal authorization headers, that a fronting proxy sanitized from the request-header section, bypassing header-based trust decisions in the application. Any http4s application using BlazeServerBuilder over HTTP/1.1 whose routes or middleware trust proxy-set headers, including X-Forwarded-For, X-Real-IP, and X-Forwarded-Host, is affected. If a fronting proxy strips or normalizes those headers but forwards chunked bodies with trailers intact, an attacker can spoof client IP for allow-lists, rate limits, or auditing, forge the https scheme, or inject internal authorization headers. A promoted Connection: close trailer is also honored, allowing attacker-controlled termination of pooled backend connections. This issue is fixed in versions 0.23.18 and 1.0.0-M42.

CVSS v3
7.4
EG Score
7.4HIGHmedium confidence
EG Risk
33
EG Risk 33/100CISA 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
Severity74% × 45%
Exploitation0% × 40%
Automatability0% × 15%
CISA SSVC: Track at low or medium mission impact; Track* at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.5%
EPSS %ILE
39th
KEV
Not listed

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

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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 9, 2026

Advisory Details (4)

Auto-updated Aug 12, 2026
Patch available. Sources: github, github_commit, github_release.
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 ef3e666c146c (http4s/blaze)

Patch available: http4s/blaze v0.23.18 (contains commit ef3e666c146c)

https://github.com/http4s/blaze/commit/ef3e666c146cfc16cb6603f1fc3c464daab4a24f
githubMentions a patch (unverified)

Chunked-body trailer fields promoted into Request.headers in blaze-server (front-end header-sanitization bypass) · Advisory · http4s/blaze · GitHub

https://github.com/http4s/blaze/security/advisories/GHSA-46q4-43ph-c6fr

Vendor Advisories for CVE-2026-73495(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:blaze-http_2.120.12.10 ... 0.23.17 (56 versions)
  • every version up to 0.23.18: fixed in 0.23.18
—
org.http4s:blaze-http_2.131.0.0-M33 ... 1.0.0-M41 (9 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:blaze-http_31.0.0-M33 ... 1.0.0-M41 (9 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
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 10× in last 7d / 46× 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 105 total refreshes for this CVE.

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  1. 2026-09-23 17:54 UTCEPSS rescore
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Related CVEs(same product + same CWE)

Same product

1 shown

Maven:org.http4s:blaze-http_2.13

Frequently asked(5)

What is CVE-2026-73495?
CVE-2026-73495 is a high vulnerability published on August 12, 2026. blaze is a Scala library for building asynchronous pipelines, with a focus on network IO. Prior to 0.23.18 and 1.0.0-M42, blaze-server can merge HTTP/1.1 chunked-body trailer fields into Request.headers. Because trailer fields are attacker-controlled, an unauthenticated remote client can inject…
When was CVE-2026-73495 disclosed?
CVE-2026-73495 was first published on August 12, 2026, with the most recent update on September 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-73495 actively exploited?
CVE-2026-73495 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (39th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-73495?
CVE-2026-73495 has a CVSS base score of 7.4 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-73495?
A fix for CVE-2026-73495 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-73495 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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