Vulnerability in granian (CVE-2026-42545)
Summary
Vulnerability in granian (CVE-2026-42545). Risk of unauthorized operations or information disclosure. Exploitable via Location. Mitigation: upgrade to 2.7.4 or later.
Original description
The description as published by the source.
Summary
Granian aborts a worker process if a WSGI application returns an invalid HTTP response header name or value. The WSGI response conversion path uses .unwrap() on both the header name and header value constructors, so malformed output from the application becomes a process abort instead of a handled error.
This issue requires a buggy or attacker-influenced WSGI application to emit invalid headers. It is not a parser bug in Granian's request path. The security impact is that application mistakes which should result in a 500 instead kill the worker process.
Details
If either conversion fails, .unwrap() panics. In release builds Granian uses panic = "abort", so the panic terminates the worker.
Preconditions
The attacker must be able to influence a header name or value produced by the WSGI application, or the application must otherwise generate invalid headers.
Examples include:
- a header name containing a space
- a header value containing
\r\n - a header value containing a null byte
These are realistic failure modes for applications that reflect user-controlled data into headers such as Location, Content Disposition, or custom response headers.
PoC
Step 1
start Granian with the PoC WSGI app
# app.py
def app(environ, start_response):
path = environ.get("PATH_INFO", "/")
if path == "/crash-name":…
Source: NIST National Vulnerability Database 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-2026-42545 has been found in granian.
Attackers can target a specific entry point like Location over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.9/10.
What to do: upgrade granian to 2.7.4 or later.
If unsure, ask your IT team or search "granian CVE-2026-42545" on the vendor's site.
CVE-2026-42545 (granian) — CWE-248 / CVSS v3 5.9
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: Location
Patched: 2.7.4 — 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-248) exists in granian. Attackers reach the vulnerable code path via Location without authentication.
Check the vendor advisory for the affected versions of granian. Attack surface: Location.
Severity: Medium (CVSS 5.9/10). Risk of unauthorized operations or information disclosure.
Update to 2.7.4.
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. Run grep -r 'granian' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'granian' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
granianを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade granian to 2.7.4ステージング環境で 2.7.4 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。
-
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
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com