CVE-2026-124540JSON-XS uncontrolled recursion
CVE-2026-124540 is a uncontrolled recursion in JSON-XS, not yet scored.
Why this priority: Not scored yet, and no exploitation signal.
Published · Updated · NVD status: Received
What it is
Deeply nested input drives recursion until the process crashes.
How it is reached
The record does not say yet how the flaw is reached; the description below is the best guide until it is scored.
What an attacker gains
Its impact has not been scored yet. In practice, this kind of flaw lets an attacker exhaust CPU, memory or connections until the service stops answering.
Is it being exploited?
There is no public report of exploitation yet.
What to do
- Upgrade JSON-XS to 4.05 or later.
Description from NVD
JSON::XS versions before 4.05 for Perl allow stack exhaustion via nested tagged values under allow_tags in decode_tag.
With allow_tags, "(" starts a tagged value. Its tag and value are decoded recursively, and each can start another tagged value. Unlike arrays and objects, this nesting is not counted against max_depth.
A run of "(" bytes exhausts the C stack and triggers an uncatchable segmentation fault regardless of max_depth.
What this means for your architecture.
A CVE names a product. Whether it matters depends on where that product sits in your systems: what reaches it, which trust boundary it guards and what it can reach once compromised. Veriom maps your components, their relationships and your trust boundaries from your code, cloud and delivery evidence, so you can see where a component like this sits. The radar itself does not look at your systems.
Components it touches
- Public entry points and shared services that must stay up. The flaw sits between untrusted traffic and shared capacity.
Trust boundaries in play
- Between untrusted traffic and shared capacity. An attacker who crosses it can exhaust CPU, memory or connections until the service stops answering.
Questions to answer about your own systems
- Where does JSON-XS run in your systems, and at which version?
- Which of those instances are reachable by people you do not trust?
- What can it reach once compromised: which data stores, secrets and services?
Sources
- CVE records and CVSS scores from the NVD CVE API. This product uses the NVD API but is not endorsed or certified by the NVD.
- Exploitation status from CISA’s Known Exploited Vulnerabilities catalog.
- Exploit likelihood from FIRST’s Exploit Prediction Scoring System (EPSS), refreshed daily.
- Explanations are written by Veriom from fixed templates over each record’s data, not by a person reviewing each CVE. Descriptions are quoted from the records as published.