CVE-2026-116272: MIME::Field::ParamVal versions before 5.521 for Perl do not flag a duplicate boundary parameter
Source GCVE Database
Not known to be exploited : upgrade to 5.521 soon.
Data as of 28 Oct 2026, 19:29 UTC
Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD
- Patch
- Available – fixed in 5.521
Exploitation evidence
Disclosed: evidence found.
CVE published 28 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade MIME-tools (Perl module) to 5.521.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| MIME-tools | Affected
| Fixed in
|
CPANMIME-toolspkg:cpan/MIME-toolsOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
If you cannot patch yet, users should be aware of this parsing discrepancy and consider additional filtering or inspection methods that do not rely solely on ambiguous_content() for detecting hidden attachments.
Description
MIME::Field::ParamVal versions before 5.521 for Perl do not properly flag duplicate boundary parameters when the parameter name contains a nested comment. This causes the parser to store such parameters under their literal names instead of the expected 'boundary' name, allowing a second boundary parameter to go undetected as a duplicate. As a result, MIME::Parser splits the message on the second boundary, while readers that skip comments per RFC 5322 take the first boundary. This discrepancy allows a remote sender to hide an attachment from filters relying on ambiguous_content(), although the recipient's mail client will display the attachment.