GHSA-p4qw-7j9g-5h53
ts-asn1-der has Incorrect DER Encoding of Numbers Leading to Denial of Service and Incorrect Value Representation
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
@apeleghq/asn1-derReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
Impact
Incorrect number DER encoding can lead to denial on service for absolute values in the range 2**31 -- 2**32 - 1. The arithmetic in the numBitLen didn't take into account that values in this range could result in a negative result upon applying the >> operator, leading to an infinite loop.
In addition, number encoding had a few other issues that resulted it in it not encoding values correctly.
Patches
The issue is patched in version 1.0.4. Users are recommended to upgrade as soon as possible.
Workarounds
If upgrading is not an option, the issue can be mitigated by validating inputs to Asn1Integer to ensure that they are not smaller than -2**31 + 1 and no larger than 2**31 - 1. Although Asn1Integer supports bigint inputs, some additional implementation issues make using bigint as a mitigation inviable, as it will result in incorrect values.
If upgrading is not an option and range checks are impractical or undesirable, input to Asn1Integer can be provided as a buffer to be used directly. Note that this requires computing the correct DER encoding externally.
References
N/A
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @apeleghq/asn1-der | all versions | 1.0.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @apeleghq/asn1-der. 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 @apeleghq/asn1-der to 1.0.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-p4qw-7j9g-5h53 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-p4qw-7j9g-5h53 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-p4qw-7j9g-5h53. 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-p4qw-7j9g-5h53 in your dependencies?
O3 detects GHSA-p4qw-7j9g-5h53 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.