CVE-2026-48824
MEDIUMCVE-2026-48824 is a medium-severity (CVSS 5.3) CWE-770 vulnerability in github.com/axllent/mailpit. O3 Security confirms whether CVE-2026-48824 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Mailpit: Sibling-endpoint memory-exhaustion DoS via unbounded JSON body on /api/v1/messages, /api/v1/tags, and /api/v1/message/{id}/release (incomplete fix of GHSA-fpxj-m5q8-fphw)
Blast Radius
github.com/axllent/mailpitReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Mailpit is an email testing tool and API for developers. Prior to version 1.30.1, the fix for GHSA-fpxj-m5q8-fphw (CVE-2026-45710, "Mailpit: Set a default 50MB p/m limit to prevent DoS via unlimited SMTP DATA and /api/v1/send body sizes") wrapped only POST /api/v1/send with http.MaxBytesReader. The four other Mailpit JSON-body API endpoints PUT /api/v1/messages (SetReadStatus), DELETE /api/v1/messages (DeleteMessages), PUT /api/v1/tags (SetMessageTags), and POST /api/v1/message/{id}/release (ReleaseMessage) still call json.NewDecoder(r.Body) directly with no body-size cap and remain reachable unauthenticated in the default docker run axllent/mailpit:latest deploy. An unauthenticated remote attacker can post a multi-million-element IDs slice and drive RSS from ~25 MiB baseline to ~450 MiB per 16 MB request body. Repeating across multiple connections accumulates the same per-request amplification per process. Version 1.30.1 contains a patch.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/axllent/mailpit | all versions | 1.30.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/axllent/mailpit. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/axllent/mailpit to 1.30.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-48824 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-48824 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-48824. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-48824 in your dependencies?
O3 detects CVE-2026-48824 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.