CPANSA-MIME-tools-2026-116265: MIME-tools vulnerability
| Publisher | giterlizzi | Document category | csaf_security_advisory |
|---|---|---|---|
| Initial release date | 2026-10-28T00:00:00 | Engine | CSAF Perl Toolkit 0.26 |
| Current release date | 2026-10-28T00:00:00 | Build Date | |
| Current version | 1 | Status | final |
| CVSS v3.1 Base Score | Severity | ||
| Original language | Language | en | |
| Also referred to | |||
Vulnerability Description
MIME::Field::ParamVal versions before 5.521 for Perl do not flag an ambiguous multipart boundary written as RFC 2231 continuations.
The boundary ambiguity checks look only at a plain boundary= parameter, and a boundary split into RFC 2231 sections (boundary*0=, boundary*1= and so on) is joined after they have run. A repeated section number is concatenated rather than reported as a duplicate. From version 5.518, an encoded word or trailing whitespace in such a boundary also goes unflagged, although multipart_boundary() decodes or strips it.
A remote sender can make MIME::Parser split a message on a different boundary than other mail readers, hiding an attachment from a filter that relies on ambiguous_content() while the recipient's mail client shows it.
Vulnerabilities
CVE-2026-116265
Vulnerability DescriptionMIME::Field::ParamVal versions before 5.521 for Perl do not flag an ambiguous multipart boundary written as RFC 2231 continuations.
The boundary ambiguity checks look only at a plain boundary= parameter, and a boundary split into RFC 2231 sections (boundary*0=, boundary*1= and so on) is joined after they have run. A repeated section number is concatenated rather than reported as a duplicate. From version 5.518, an encoded word or trailing whitespace in such a boundary also goes unflagged, although multipart_boundary() decodes or strips it.
A remote sender can make MIME::Parser split a message on a different boundary than other mail readers, hiding an attachment from a filter that relies on ambiguous_content() while the recipient's mail client shows it.
| Weakness | CWE-436 : Interpretation Conflict |
|---|
Product status
Known affected
| Product | Score | ||||
|---|---|---|---|---|---|
| MIME-tools less than 5.521 |
|
Fixed
- MIME-tools greater than or equal 5.521
giterlizzi
Namespace: https://github.com/giterlizzi/
gdt@cpan.org
References
- CPANSA-MIME-tools-2026-116265 JSON self
https://raw.githubusercontent.com/giterlizzi/perl-CPANSA-CSAF/develop/csaf/white/2026/cpansa-mime-tools-2026-116265.json - https://metacpan.org/release/DSKOLL/MIME-tools-5.521/changes external
https://metacpan.org/release/DSKOLL/MIME-tools-5.521/changes - CVE-2026-116265 (NVD) external
https://nvd.nist.gov/vuln/detail/CVE-2026-116265
Revision history
| Version | Date of the revision | Summary of the revision |
|---|---|---|
| 1 | Wed Oct 28 00:00:00 2026 | First release |
Sharing rules
TLP:WHITE
For the TLP version see: https://www.first.org/tlp/