CVSS 4.0
6.9 mediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:NCVE-2026-121946
Medium (6.9).
zbateson mail-mime-parser before 3.0.9 and 4.x before 4.0.6 contains a CRLF header injection vulnerability in message-building helpers that fail to strip CR and LF characters. Attackers supplying crafted MIME type, charset, encoding, micalg, or protocol values can inject extra header lines such as a forged Bcc into outgoing messages.
Severity
CVSS 3.1
7.2 highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N- CISA's assessment (SSVC)
- Exploitation: PoC · Automatable: yes · Technical impact: partial, assessed 2026-11-04. From CISA's Vulnrichment in the CVE List: whether it is exploited, whether exploiting it can be automated, and how much control it gives.
- CWE
- CWE-93 Improper Neutralization of CRLF Sequences (CRLF Injection)
- OWASP Top 10
- A05:2025 Injection
- Published
- Modified
- Record from
- the NVD, synced
Ask an AI about this CVE
Show the prompt
Explain CVE-2026-121946 for an engineer deciding whether to act. Use https://cve.bz/api/public/cves/CVE-2026-121946?via=ask-ai-copy and https://cve.bz/cve/CVE-2026-121946?via=ask-ai-copy as the source of truth: what is affected and which versions fix it, whether it is in CISA KEV, public exploits, and its EPSS (an internet-wide 30-day estimate of exploitation activity, not a forecast for my systems). If they give no fixed versions, use the CVE record https://cveawg.mitre.org/api/cve/CVE-2026-121946 or the vendor advisory, not third-party mirrors. Tell me how to check whether I am affected and how to verify a fix. Cite the sources and say where they are uncertain.Opens a third-party assistant; its answer is its own, not cve.bz's. The prompt holds only this CVE's id and public links.
Versions
From the CNA's record in the CVE List.
| Product | Affected |
|---|---|
| zbateson mail-mime-parser | from 0.3.0 before 3.0.9 |
| zbateson mail-mime-parser | from 4.0.0 before 4.0.6 |
Attack patterns (CAPEC)
- CAPEC-15 Command Delimiters Likelihood: High · Severity: High
- CAPEC-81 Web Server Logs Tampering Likelihood: Medium · Severity: High
The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.
References
- https://github.com/zbateson/mail-mime-parser/blob/4.0.5/src/Message/Helper/MultipartHelper.php#L270-L273
- https://github.com/zbateson/mail-mime-parser/commit/1fa840ef367958e991e6840b4e3ffd41aca9d147
- https://github.com/zbateson/mail-mime-parser/commit/b032920875c6cb35bb2ddd7abfd7e98608d75bc0
- https://github.com/zbateson/mail-mime-parser/commit/c31c62ccc3e66a7a7da0d79954ef83807f9daa20
- https://github.com/zbateson/mail-mime-parser/commit/f385b2923023a9a7b69003468e363a4661f1c85a
- https://github.com/zbateson/mail-mime-parser/security/advisories/GHSA-gmgm-r6fh-fq6g
- https://www.vulncheck.com/advisories/zbateson-mail-mime-parser-before-3.0.9-and-4-x-before-4.0.6-crlf-header-injection-via-message-builders