VulnerabilityPublished 24 Sep 2026Updated 5 Oct 2026

CVE-2026-61815: zbateson mail-mime-parser · CRLF Injection

Affects zbateson mail-mime-parserSource CVE Database V5

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Not known to be exploited · CVSS 7.2 High : upgrade to 4.0.2 or 3.0.6 soon.

Data as of 7 Nov 2026, 23:24 UTC

CVSS 3.1 base score

7.2High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 4.0.2, 3.0.6

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Changed
Confidentiality: Low
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 24 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 8 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade mail-mime-parser and zbateson/mail-mime-parser to 4.0.2 or 3.0.6.

Affected software

Product	Affected	Fixed in
zbatesonmail-mime-parser	Affected >=4.0.0 <4.0.2	Fixed in 4.0.2
zbatesonmail-mime-parser	Affected <3.0.6	Fixed in 3.0.6
Packagistzbateson/mail-mime-parser`pkg:composer/zbateson/mail-mime-parser`Other threats	Affected <3.0.6 >=4.0.0 <4.0.2	Fixed in 3.0.6 4.0.2

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available in zbateson mail-mime-parser versions 3.0.6 and 4.0.2. Users should upgrade to these versions to remediate the vulnerability. For users unable to upgrade immediately, it is recommended to sanitize attachment filenames by stripping carriage-return and line-feed characters before passing them to attachment APIs or reusing them in constructed messages, for example using preg_replace('/[\r\n]+/', ' ', $filename).

Description

CVE-2026-61815 is a CRLF injection vulnerability in the zbateson mail-mime-parser library affecting versions prior to 3.0.6 and between 4.0.0 and before 4.0.2. The flaw allows attacker-controlled attachment filenames containing carriage-return and line-feed characters to inject additional MIME headers, potentially enabling header injection attacks such as forged Bcc headers. This impacts applications that parse and re-send MIME messages using this library without sanitizing attachment filenames. Versions 3.0.6 and 4.0.2 include patches for this issue. Users of older 1.x and 2.x versions are advised to upgrade or sanitize filenames to mitigate risk.

Impact

An attacker can inject additional MIME headers by including CRLF sequences in attachment filenames, potentially leading to header injection attacks such as forging Bcc headers that could silently exfiltrate outgoing messages. This compromises confidentiality and integrity of email messages processed by vulnerable versions of the library. The CVSS score of 7.2 (high) reflects the network attack vector, low complexity, no privileges required, no user interaction, and impact on confidentiality and integrity.

Summary

The zbateson mail-mime-parser library suffers from improper neutralization of CRLF sequences (CWE-93) in attachment filenames used in MIME message headers. Specifically, filenames containing CR/LF characters are interpolated into Content-Type and Content-Disposition headers without stripping these characters, allowing injection of additional attacker-controlled headers. This vulnerability affects versions prior to 3.0.6 and versions from 4.0.0 up to but not including 4.0.2. The vulnerability is exploitable when an application re-attaches or forwards parsed MIME messages containing attacker-influenced filenames. The issue is patched in versions 3.0.6 and 4.0.2. Users on unsupported 1.x and 2.x branches should upgrade or sanitize filenames by removing CR and LF characters before use.

CWE-93Improper Neutralization of CRLF Sequences (CRLF Injection) (opens in a new tab)
Base weaknessOWASP Top 10 A05:2025: Injection (opens in a new tab)
The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs.
Implementation
Avoid using CRLF as a special sequence.
Implementation
Appropriately filter or quote CRLF sequences in user-controlled input.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
Deserialization (opens in a new tab)
Injection Prevention (opens in a new tab)
SQL Injection Prevention (opens in a new tab)
Injection Prevention in Java (opens in a new tab)
OWASP ASVS 4.0.3
V1.5.1 (opens in a new tab)
Attack patterns
Command Delimiters (opens in a new tab)
Web Server Logs Tampering (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/zbateson/mail-mime-parser/security/advisories/GHSA-36h5-qg4p-q2qf (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 8 Oct 2026, 21:06 UTC

WeaknessesCWE-93

Technical details

References

Community reviews

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