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.
Analysis
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Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| unaffected |
|
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Vendor Solution
Upgrade to MIME-tools 5.521 or later.
Tracking
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| Link | Providers |
|---|---|
| https://metacpan.org/release/DSKOLL/MIME-tools-5.521/changes |
|
Wed, 28 Oct 2026 17:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | MIME::Field::ParamVal versions before 5.521 for Perl do not flag an ambiguous multipart boundary written as RFC 2231 continuations | |
| Weaknesses | CWE-436 | |
| References |
|
Subscriptions
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MITRE
Status: PUBLISHED
Assigner: CPANSec
Published:
Updated: 2026-10-28T17:32:11.827Z
Reserved: 2026-10-25T18:05:02.235Z
Link: CVE-2026-116265
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-10-28T18:17:12.910
Modified: 2026-10-28T18:17:12.910
Link: CVE-2026-116265
Redhat
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OpenCVE Enrichment
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