GHSA-rcx8-48pc-v9q8
mail-internals use-after-free vulnerability in `vec_insert_bytes`
Blast Radius
mail-internalsReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
Incorrect reallocation logic in the function vec_insert_bytes causes a use-after-free.
This function does not have to be called directly to trigger the vulnerability because many methods on EncodingWriter call this function internally.
The mail-* suite is unmaintained and the upstream sources have been actively vandalised.
A fixed mail-internals-ng (and mail-headers-ng and mail-core-ng) crate has been published which fixes this, and a dependency on another unsound crate.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | mail-internals | ≥ 0.2.0 | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mail-internals. 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.
Remediation status
No patched version of mail-internals has shipped for GHSA-rcx8-48pc-v9q8 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
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 GHSA-rcx8-48pc-v9q8 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 GHSA-rcx8-48pc-v9q8. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-rcx8-48pc-v9q8 in your dependencies?
O3 detects GHSA-rcx8-48pc-v9q8 across crates.io dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.