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.
CVE-2026-73495
“—” beside the score: it is equal to the CVSS score beside it.
Score 7.4 from GitHub Security Advisory (severity: HIGH) published 2026-07-24. A secondary CVSS source baseline 7.4; sources differ by 0.0.
Also known asEUVD-2026-57635 (ENISA EUVD) · GHSA-46q4-43ph-c6fr (GitHub Security Advisories)Source: ENISA EUVD
- High severity, but no confirmed exploitation yet
A fix is available — apply it.
- CVSS v3
- 7.4
- EG Score
- 7.4HIGHmedium confidence
- EG Risk
- 33EG Risk 33/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity74% × 45%Impact severity (EG Severity): CVSS 7.4 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0.5% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability0% × 15%CISA's SSVC Automatable value: no (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines. - EPSS PROB
- 0.5%
- EPSS %ILE
- 41st
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (7.4): severity, escalated by confirmed exploitation. This CVE's 7.4 is its impact severity (EG Severity), not escalated.
- EG Severity
- 7.4 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track 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). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
August 12, 2026
Last Modified
October 24, 2026
Advisory Details (4)
Auto-updated Aug 12, 2026v1.0.0-M42
Patch available: http4s/blaze v1.0.0-M42 (pre-release)
https://github.com/http4s/blaze/releases/tag/v1.0.0-M42v0.23.18
Patch available: http4s/blaze v0.23.18
https://github.com/http4s/blaze/releases/tag/v0.23.18commit ef3e666c146c (http4s/blaze)
Patch available: http4s/blaze v0.23.18 (contains commit ef3e666c146c)
https://github.com/http4s/blaze/commit/ef3e666c146cfc16cb6603f1fc3c464daab4a24fChunked-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-c6frVendor 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.
Patch Availability(2)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| maven | org.http4s:blaze-http_2.12 @ 0.23.18 (fixes <= 0.23.17) | — | ghsa |
| maven | org.http4s:blaze-http_2.13 @ 1.0.0-M42 (fixes >= 1.0.0-M1, <= 1.0.0-M41) | — | ghsa |
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Affected Packages
(3 across 1 ecosystem)
Maven(3)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| org.http4s:blaze-http_2.12 | 0.12.10 ... 0.23.17 (56 versions) |
| — |
| org.http4s:blaze-http_2.13 | 1.0.0-M33 ... 1.0.0-M41 (9 versions) |
| — |
| org.http4s:blaze-http_3 | 1.0.0-M33 ... 1.0.0-M41 (9 versions) |
| — |
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 time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
Showing the most recent 99 of 138 refreshes on record for this CVE.
A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 1 repeat row among the latest 100 is merged into the row it repeats. The 39 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-11-01 07:39 UTCEG score recompute
- 2026-11-01 07:39 UTCGHSA enrichmentGHSA-46q4-43ph-c6fr · GitHub severity HIGH · GitHub CVSS 7.4
- 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-10-31 13:56 UTCEG score recompute
- 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-10-25 14:05 UTCEG score recompute
- 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-23 19:31 UTCEG score recompute
- 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-20 08:29 UTCEG score recompute
- 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
- 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-18 03:15 UTCEG score recompute
- 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.5% · 39th percentile
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- 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.5% · 39th percentile
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- 2026-10-13 07:53 UTCEG score recompute
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- 2026-10-12 15:40 UTCEG score recompute
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- 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.5% · 39th percentile
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- 2026-10-07 01:21 UTCEG score recompute
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- 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.5% · 38th percentile
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- 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.5% · 38th percentile
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- 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.3% · 21st percentile
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- 2026-09-12 15:02 UTCEPSS rescoreEPSS 0.3% · 21st percentile
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- 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.3% · 21st percentile
- 2026-09-10 19:48 UTCEG score recompute
- 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.3% · 21st percentile
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- 2026-09-04 05:07 UTCEPSS rescoreEPSS 0.3% · 21st percentile
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- 2026-08-30 19:18 UTCEPSS rescoreEPSS 0.3% · 21st percentile
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Frequently asked(5)
What is CVE-2026-73495?
When was the CVE record for CVE-2026-73495 published?
Is CVE-2026-73495 actively exploited?
What is the CVSS score of CVE-2026-73495?
How do I remediate CVE-2026-73495?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-73495
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