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CVE-2026-54770 medium CVSS 6.1

Open Redirect in webob (CVE-2026-54770)

Summary

Vulnerability in webob (CVE-2026-54770). Risk of unauthorized operations or information disclosure. Exploitable via Location. Mitigation: upgrade to 1.8.11 or later.

Original description

The description as published by the source.

Summary

This is a third follow-up to CVE-2024-42353 / GHSA-mg3v-6m49-jhp3
and CVE-2026-44889 / GHSA-fh3h-vg37-cc95.

WebOb makes the Location header absolute when it serves a redirect. To stop a
relative or protocol-relative target from redirecting users off-host, it checks
the value for a URI scheme and for a leading //, then joins it against the
request URI with urllib.parse.urljoin(). The previous fix additionally stripped
ASCII tab/CR/LF from the value before those checks.

However, on Python 3.10+ urllib.parse.urljoin() (via urlsplit()) does more
than remove tab/CR/LF: it also strips leading and trailing C0 control
characters (U+0000–U+001F) and spaces from the URL before parsing it.
Because WebOb's guard checks (SCHEME_RE and startswith("//")) run against the
un-stripped value, a single leading space or control byte slips past them, and
urljoin() then silently removes that byte and parses what remains as a
protocol-relative — or even absolute — URL. The result is an open redirect to an
attacker-controlled host.

Details

Response._make_location_absolute() (in src/webob/response.py) performed,
prior to the fix:

value = value.replace("\t", "").replace("\r", "").replace("\n", "")

if SCHEME_RE.search(value):          # ^[a-z]+:   -> already absolute, return as-is
    return value

if value.startswith("//"):           # neutralize protocol-relative URLs
    value = f"/%2f{value[2:]}"

new_location = urlparse.urljoin(_r…

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-2026-54770 has been found in webob.
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: 6.1/10.
What to do: upgrade webob to 1.8.11 or later.
If unsure, ask your IT team or search "webob CVE-2026-54770" on the vendor's site.

CVE-2026-54770 (webob) — CWE-601 / CVSS v3 6.1
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: Location / SCHEME_RE / Response.location / webob.exc._HTTPMove
Patched: 1.8.11 — 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.

❓ What is the problem

A vulnerability (CWE-601) exists in webob. Attackers reach the vulnerable code path via Location without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of webob. Attack surface: Location / SCHEME_RE / Response.location / webob.exc._HTTPMove.

🔥 Severity

Severity: Medium (CVSS 6.1/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 1.8.11.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'webob' . 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

  1. 1
    Identify exposure identify 
    grep -r 'webob' . | 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 webob を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade webob to 1.8.11

    ステージング環境で 1.8.11 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。

  3. 3
    Post-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

pip webob
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.8.11"}]}]

References

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