CVE-2026-121946
What it is
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.
At a glance
- Exploitability
- Can be exploited over the network without logging in. Limited direct impact.
- Exploit odds
- 0.3% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- ReservedThe CVE id was reserved by its CNA
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 0.3% in the next 30 days (EPSS).
- Severity: 6.9 MEDIUM (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 0.3% · EPSS, next 30 days
- Weakness
- CWE-93
- Record status
- Received
Attack profile CVSS 4.0 · 6.9
- Attack vector
- Network
- Complexity
- Low
- Attack requirements
- None
- Privileges needed
- None
- User interaction
- None
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
Raw vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2026-121946.md and follow it. Check whether this project is affected by CVE-2026-121946. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- 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://github.com/zbateson/mail-mime-parser/security/advisories/GHSA-gmgm-r6fh-fq6g
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
- https://github.com/zbateson/mail-mime-parser/security/advisories/GHSA-gmgm-r6fh-fq6g