Is CVE-2026-116272 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-116272 being exploited in the wild.

How severe is CVE-2026-116272?

Informational severity, published 28 October 2026.

Is there a fix for CVE-2026-116272?

Yes: fixed in 5.521. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-116272 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-116272?

Check whether you run Perl MIME-tools at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-116272: MIME-tools MIME::Parser duplicate boundary detection bypass with comments

CVE-2026-116272 · Severity: info · Published 2026-10-28

MIME-tools is a Perl library for parsing email messages. A flaw in versions before 5.521 allows attackers to bypass content filters by hiding attachments using a malformed boundary parameter containing nested comments. An attacker can send a crafted email where a filter checking for problematic content sees one version, but the recipient's mail client displays a different version with hidden attachments.

Technologies: Perl MIME-tools. Vendors: Perl.

Quick answers

Is CVE-2026-116272 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-116272 being exploited in the wild.
How severe is CVE-2026-116272?: Informational severity, published 28 October 2026.
Which products and versions are affected?: Perl MIME-tools before 5.521.
Is there a fix for CVE-2026-116272?: Yes: fixed in 5.521. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-116272 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-116272?: Check whether you run Perl MIME-tools at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

Fixed in: 5.521

Technical details

MIME::Parser fails to normalize boundary parameter names containing RFC 5322 comments (nested parentheses), storing them under literal names like "boundary((c))" instead of "boundary". This allows a second boundary parameter to evade duplicate detection. Readers that correctly strip comments parse the first boundary, while the parser sees an undetected second one, creating message-splitting ambiguity. An attacker exploits this via network delivery of a crafted MIME message to bypass ambiguous_content() checks.

Affected products

Perl MIME-tools before 5.521

Timeline

2026-10-28: disclosed
2026-10-27: patched

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.