Vulnerability in @logtape/syslog (CVE-2026-54511)
Summary
Vulnerability in @logtape/syslog (CVE-2026-54511). Data can be tampered with by attackers. Mitigation: upgrade to 1.3.11 or later.
Original description
The description as published by the source.
@logtape/syslog contains two related output-encoding bugs in the structured data formatting code. Both only affect deployments with includeStructuredData: true, which is non-default.
1. Unescaped C0 control characters in structured data values
escapeStructuredDataValue() in packages/syslog/src/syslog.ts escapes \, ", and ] per RFC 5424 but does not escape newline (\n), carriage return (\r), or any other C0 control characters (U+0000–U+001F):
function escapeStructuredDataValue(value: string): string {
return value
.replace(/\\/g, "\\\\")
.replace(/"/g, '\\"')
.replace(/]/g, "\\]");
// \n, \r, and other C0 control characters are not escaped
}
TCP syslog commonly uses \n as a frame delimiter (RFC 6587, non-transparent framing). If an attacker-controlled value contains a literal newline, that newline terminates the current syslog frame. Bytes following the newline begin a new frame, and if they form a valid RFC 5424 header (1 …), a downstream collector will accept them as a separate, authentic-looking syslog record.
2. Unvalidated SD-NAME keys
Structured data parameter keys are inserted into the message without validation or escaping:
elements.push(`${key}="${escapedValue}"`);
RFC 5424 defines SD-NAME as printable US-ASCII characters excluding =, ], ", and space, with a maximum length of 32. A key containing any of those characters, control characters, or exceeding the length limit will…
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-2026-54511 has been found in @logtape/syslog.
Data can be tampered with by attackers. CVSS score: 8.6/10.
What to do: upgrade @logtape/syslog to 1.3.11 or later.
If unsure, ask your IT team or search "@logtape/syslog CVE-2026-54511" on the vendor's site.
CVE-2026-54511 (@logtape/syslog) — CWE-93 / CVSS v3 8.6
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 1.3.11 — 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.
A vulnerability (CWE-93) exists in @logtape/syslog.
Check the vendor advisory for the affected versions of @logtape/syslog.
Severity: High (CVSS 8.6/10). Data can be tampered with by attackers.
Update to 1.3.11.
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 '@logtape/syslog' . 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 '@logtape/syslog' . | 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
@logtape/syslog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 @logtape/syslog to 1.3.11ステージング環境で 1.3.11 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。
-
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
- web github.com