Vulnerability in morgan (CVE-2026-87859)
Summary
Vulnerability in morgan (CVE-2026-87859). Risk of unauthorized operations or information disclosure. Exploitable via combined. Mitigation: upgrade to 1.12.1 or later.
Original description
The description as published by the source.
Impact
Morgan writes attacker-controlled request data to the access log. Its escaping (added in 1.11.0 and 1.12.0) neutralizes control characters, the Unicode line separators, and backslash, but not the double quote (0x22), which is the field delimiter of the Apache combined log format morgan emits. An attacker who controls a quoted field (:user-agent, :referrer, the request URL, or the Basic auth :remote-user) can inject a double quote to close the field early and forge additional fields in the log record. The combined, common, and default formats, and any custom format that quotes a token, are affected. This is an incomplete fix of CVE-2026-5078 and CVE-2026-15603.
Patches
Users should upgrade to version 1.12.1.
Workarounds
Update to version 1.12.1.
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-2026-87859 has been found in morgan.
Attackers can target a specific entry point like combined over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.3/10.
What to do: upgrade morgan to 1.12.1 or later.
If unsure, ask your IT team or search "morgan CVE-2026-87859" on the vendor's site.
CVE-2026-87859 (morgan) — CWE-117 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: combined / common / default
Patched: 1.12.1 — 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-117) exists in morgan. Attackers reach the vulnerable code path via combined without authentication.
Check the vendor advisory for the affected versions of morgan. Attack surface: combined / common / default.
Severity: Medium (CVSS 5.3/10). Risk of unauthorized operations or information disclosure.
Update to 1.12.1.
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 'morgan' . 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 'morgan' . | 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
morgan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 morgan to 1.12.1ステージング環境で 1.12.1 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
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-87859 node-morgan
- Ubuntu UBUNTU-CVE-2026-87859 node-morgan
References
- web cna.openjsf.org
- web github.com
- web nvd.nist.gov
- web github.com
- web github.com
- web github.com