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No exploitation reportedFix availableAwaiting NVD analysis

CVE-2026-116265

MIME::Field::ParamVal versions before 5.521 for Perl do not flag an ambiguous multipart boundary written as RFC 2231 continuations

No exploitation reported by the sources we read.

  • Published2026-10-28
  • WeaknessCWE-436

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2026-10-2817:32CVE publishedCNA

Versions per branch

Products declared by the CNA1 product

As CPANSec, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-10-28

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • libmime-tools-perlUbuntu:26.10all versions · no fixed version listed
  • libmime-tools-perlUbuntu:26.04:LTSall versions · no fixed version listed
  • libmime-tools-perlUbuntu:24.04:LTSall versions · no fixed version listed
  • libmime-tools-perlUbuntu:22.04:LTSall versions · no fixed version listed
  • libmime-tools-perlUbuntu:20.04:LTSall versions · no fixed version listed
  • libmime-tools-perlUbuntu:18.04:LTSall versions · no fixed version listed
  • libmime-tools-perlUbuntu:16.04:LTSall versions · no fixed version listed
  • libmime-tools-perlUbuntu:14.04:LTSall versions · no fixed version listed

5 more package ranges on OSV.dev

Vendor advisories

  • CVE-2026-116265 Red Hat Product Security1 known affected

    perl-MIME-tools: perl-MIME-tools: Security filter bypass via ambiguous multipart boundary continuations

    perl-MIME-tools.src as a component of Red Hat Enterprise Linux 6

Full record on NVD

Fix

  1. No fix planned, says the vendor Red Hat Product Security CVE-2026-116265 · 1 productOut of support scope

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Published
2026-10-28
Last Modified
2026-11-05
NVD status
Awaiting Analysis
GitHub Advisory
GHSA-7m3r-rg8x-jrmh

Frequently asked questions

What is CVE-2026-116265?

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.

Is CVE-2026-116265 actively exploited?

Active exploitation of CVE-2026-116265 has not been confirmed. Its EPSS score was 0.2% on 2026-11-05, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-116265?

CVE-2026-116265 has a CVSS v3 base score of 5.3 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

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