Answer in brief
CVE-2026-116264 records a Unknown severity vulnerability in MIME::Field::ParamVal versions before 5.521 for Perl allow one invalid Content-Type parameter to hide the parameters after it, including the multipart boundary. The current sources do not mark it as known exploited. The current feed maps MIME-tools (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps MIME-tools (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| MIME-toolsgeneric | >=0 <5.521 | 5.521 |
Published upstream
Oct 28, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 28, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 28, 2026
MIME::Field::ParamVal versions before 5.521 for Perl allow one invalid Content-Type parameter to hide the parameters after it, including the multipart boundary. Parameter parsing stops at the first parameter whose name it cannot read, such as x:y=1 or a name containing an 8-bit byte, and drops every parameter after it. When the boundary is among them, MIME::Parser keeps the multipart body as a single undecoded part without marking the parse as ambiguous. Mail readers that skip the invalid parameter still find the boundary. A remote sender can hide an attachment from a filter that relies on ambiguous_content() while the recipient's mail client shows it.
Quoted source text, attributed separately from HOL analysis.