MIME::Head versions from 5.518 before 5.521 for Perl decode a partly encoded multipart boundary without flagging the parse as ambiguous
Impact
MIME::Head versions 5.518 before 5.521 for Perl decode partly encoded multipart boundaries without flagging the parse as ambiguous, allowing a remote sender to hide attachments. The weakness is an interpretation conflict. The impact is uncertain.
Summarized by @cf/meta/llama-3.3-70b-instruct-fp8-fast. Verify details against the original sources.What to do
Upgrade to MIME-tools 5.521 or later.
Affected packages
Affected products
Vendor version evidence. Product records are separate from automatic dependency matching.
Vendor not supplied · CPANSec
MIME-tools
1 range
Vendor not supplied · CPANSec
MIME-tools
Package identity
pkg:cpan/MIME-toolsIdentity supplied by CPANSec. Version matching requires compatible range evidence.
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affected
5.518 → before 5.521
custom versions
Other versions: unaffected
Original source description
MIME::Head versions from 5.518 before 5.521 for Perl decode a partly encoded multipart boundary without flagging the parse as ambiguous.
The multipart_boundary() method decodes RFC 2047 encoded words anywhere in the boundary, but the ambiguity check only fires when the whole value is one encoded word. A boundary such as abc=?us-ascii?Q?def?= is used as abcdef, and ambiguous_content() returns false.
Encoded words are not allowed in parameters, so other mail readers split the message on the literal value. A remote sender can hide an attachment from a filter that relies on ambiguous_content() while the recipient's mail client shows it.
Inside the record
Evidence available
Describes the evidence in this view, not whether the product is safe.
Original records
CVE-2026-116266View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.
cve.new JSON →Underlying weaknesses
The source’s classification of what caused the vulnerability.
Contributing organizations · 1
Assigning organization
What changed
Follow changesLarge field values are marked as truncated previews. Original source snapshots remain retained.