GHSA-x462-89pf-6r5h is a high-severity (CVSS 7.5) Improper Input Validation vulnerability in github.com/syncthing/syncthing. O3 Security confirms whether GHSA-x462-89pf-6r5h is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Crash due to malformed relay protocol message
Real-World Exposure
github.com/syncthing/syncthingReal-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
Impact
-
syncthingcan be caused to crash and exit if sent a malformed relay protocol message message with a negative length field. -
The relay server
strelaysrvcan be caused to crash and exit if sent a malformed relay protocol message with a negative length field.
At no point is sensitive data exposed or liable to be altered due to this issue. Sensitive data is never exposed to relay operators. Syncthing itself would need to be lured to connect to a malicious relay server in order to exploit the issue.
Patches
Fixed in version 1.15.0.
Workarounds
-
No known workaround for
strelaysrv. -
syncthingcan be configured to not use relays, or to only use specific, trusted relays. If Syncthing is used in a closed environment or with relaying disabled, i.e., it does not communicate with unknown relays, Syncthing is not vulnerable.
For more information
If you have any questions or comments about this advisory, please discuss it on the forum.
Thanks to Wojciech Paciorek for discovering and reporting this issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/syncthing/syncthing | all versions | 1.15.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/syncthing/syncthing. 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/syncthing/syncthing to 1.15.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-x462-89pf-6r5h 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 GHSA-x462-89pf-6r5h 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-x462-89pf-6r5h. 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-x462-89pf-6r5h in your dependencies?
O3 detects GHSA-x462-89pf-6r5h across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.