CVE-2026-116265 MIME::Field::ParamVal versions before 5.521 for Perl do not flag an ambiguous multipart boundary written as RFC 2231 continuations.
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2026-116265?
CVE-2026-116265 is a vulnerability, published on 28 Oct 2026.
Official 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.
Weakness: CWE-436
Which versions are affected by CVE-2026-116265?
How do I fix CVE-2026-116265?
No fix has been published for CVE-2026-116265 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-116265 being exploited?
There is no known exploitation of CVE-2026-116265 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-116265, GHSA-7m3r-rg8x-jrmh, UBUNTU-CVE-2026-116265.