Vulnerability in eml_parser (CVE-2026-55620)
Summary
Vulnerability in eml_parser (CVE-2026-55620). Risk of unauthorized operations or information disclosure. Exploitable via eml_parser. Mitigation: upgrade to 3.0.2 or later.
Original description
The description as published by the source.
Summary
eml_parser strips parenthesised CFWS comments from Received: headers using a regex-based fix-point loop. The loop has quadratic time complexity in the number of nested parens. A single Received: header containing 5,000 nested parens causes ~1.3 seconds of CPU saturation per parsed message; runtime quadruples per doubling of nesting depth.
Impact
This represents a CPU exhaustion DoS in any pipeline that processes attacker-supplied EML files. An attacker can create relatively small EML files that will take multiple seconds to parse.
This is particularly problematic for synchronous email-processing pipelines (gateways, sandboxes, real-time triage) where worker latency directly translates to queue backpressure and possible service-level outages.
Patches
Since version 3.0.2, eml_parser uses a linear-time algorithm to remove the comments from Received: headers.
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-2026-55620 has been found in eml_parser.
Attackers can target a specific entry point like eml_parser over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade eml_parser to 3.0.2 or later.
If unsure, ask your IT team or search "eml_parser CVE-2026-55620" on the vendor's site.
CVE-2026-55620 (eml_parser) — CWE-770 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: eml_parser
Patched: 3.0.2 — 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-770) exists in eml_parser. Attackers reach the vulnerable code path via eml_parser without authentication.
Check the vendor advisory for the affected versions of eml_parser. Attack surface: eml_parser.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to 3.0.2.
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 'eml_parser' . 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
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1Identify exposure identify
grep -r 'eml_parser' . | 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
eml_parser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 eml_parser to 3.0.2ステージング環境で 3.0.2 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。