Quick answers
- Is CVE-2026-116270 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-116270 being exploited in the wild.
- How severe is CVE-2026-116270?
- Informational severity, published 28 October 2026.
- Which products and versions are affected?
- CPAN MIME::Words before 5.521.
- Is there a fix for CVE-2026-116270?
- Yes: fixed in 5.521. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-116270 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-116270?
- Check whether you run CPAN MIME::Words 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
The decode_mimewords function in MIME::Words before version 5.521 appends the entire input string to the $@ error variable for each incomplete encoded-word sequence ("=?" without a complete encoding header). A crafted Content-Type header with 8,000 such sequences (16 KB of data) results in approximately 128 MB of error strings, causing unbounded memory growth. From MIME::Words 5.518 onwards, MIME::Parser decodes every multipart boundary through this vulnerable function, allowing remote exploitation via email headers.
Affected products
- CPAN MIME::Words before 5.521
Timeline
- 2026-10-28: disclosed
- 2026-10-27: patched: Version 5.521 released with fix to stop copying input into error messages