Vulnerability in org.http4s:blaze-http_2.13 (CVE-2026-73495)
Summary
Vulnerability in org.http4s:blaze-http_2.13 (CVE-2026-73495). Confidential information can be exposed externally. Exploitable via Request.headers. Mitigation: upgrade to 1.0.0-M42 or later.
Original description
The description as published by the source.
Summary
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/values (e.g. X-Forwarded-For, internal-auth headers) that a fronting proxy sanitized from the request-header section, bypassing header-based trust decisions in the application.
Impact
Any http4s application using BlazeServerBuilder over HTTP/1.1 whose routes or middleware trust proxy-set headers (e.g., X-Forwarded-For, X-Real-IP, X-Forwarded-Host, org-internal auth headers) is affected. Where a fronting proxy strips/normalizes those headers but forwards chunked bodies with trailers intact, an attacker can spoof client IP for allow-lists/rate-limits/audit, forge the https scheme, or inject internal-auth headers. A promoted Connection: close trailer is also honored, allowing attacker-controlled termination of pooled backend connections.
Workarounds
Deploy behind a proxy that removes trailer fields (or rejects requests that use trailers) before forwarding; until patched, avoid trust decisions based on headers that a proxy is relied upon to sanitize.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-73495 has been found in org.http4s:blaze-http_2.13.
Attackers can target a specific entry point like Request.headers over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 7.4/10.
What to do: upgrade org.http4s:blaze-http_2.13 to 1.0.0-M42 or later.
If unsure, ask your IT team or search "org.http4s:blaze-http_2.13 CVE-2026-73495" on the vendor's site.
CVE-2026-73495 (org.http4s:blaze-http_2.13) — CWE-444 / CVSS v3 7.4
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: Request.headers / BlazeServerBuilder / https
Patched: 1.0.0-M42 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-444) exists in org.http4s:blaze-http_2.13. Attackers reach the vulnerable code path via Request.headers without authentication.
Check the vendor advisory for the affected versions of org.http4s:blaze-http_2.13. Attack surface: Request.headers / BlazeServerBuilder / https.
Severity: High (CVSS 7.4/10). Confidential information can be exposed externally.
Update to 1.0.0-M42.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで org.http4s:blaze-http_2.13 を使っているサービスとバージョンを洗い出す。
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2Apply patch patch
Upgrade org.http4s:blaze-http_2.13 to 1.0.0-M42ステージング環境で 1.0.0-M42 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
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3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- package github.com
- web github.com
- web github.com
- web github.com
- web github.com
- web github.com