CVE-2026-124016 postal-mime < 4.2.1 Algorithmic Complexity DoS via processLine
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2026-124016?
CVE-2026-124016 is a medium-severity vulnerability in postalsys postal-mime, published on 10 Nov 2026.
Official description
postal-mime before 4.2.1 contains an algorithmic complexity denial of service vulnerability that allows unauthenticated remote attackers to cause excessive CPU consumption in the PostalMime.processLine() function by crafting deeply nested multipart email messages with boundary lines sharing long prefixes with open boundaries. Attackers can deliver a malicious email with nesting up to the default maxNestingDepth of 256, causing per-line parsing cost to scale as O(depth x shared prefix length) and blocking the Node.js event loop for seconds per message.
Weakness: CWE-407
Which versions are affected by CVE-2026-124016?
How do I fix CVE-2026-124016?
No fix has been published for CVE-2026-124016 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-124016 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-124016 exists.
Sources
Also known as GHSA-2h8j-5q45-j7q7, GHSA-q8wm-54mj-r36p.