Is CVE-2026-124586 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-124586 being exploited in the wild.

How severe is CVE-2026-124586?

High severity, with a CVSS score of 7.3, published 9 November 2026.

Is there a fix for CVE-2026-124586?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-124586 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-124586?

Check whether you run Tencent RapidJSON at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-124586: Tencent RapidJSON out-of-bounds read in floating-point parsing

CVE-2026-124586 · Severity: high · CVSS 7.3 · Published 2026-11-09

RapidJSON is a widely-used C++ JSON parsing library. A flaw in full-precision floating-point number parsing allows attackers to trigger an out-of-bounds memory read by crafting malicious JSON input, potentially leading to information disclosure or application crash. The vulnerability can be exploited remotely and has been publicly disclosed.

Vendors: Tencent.

Quick answers

Is CVE-2026-124586 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-124586 being exploited in the wild.
How severe is CVE-2026-124586?: High severity, with a CVSS score of 7.3, published 9 November 2026.
Which products and versions are affected?: Tencent RapidJSON 1.1.0.
Is there a fix for CVE-2026-124586?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-124586 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-124586?: Check whether you run Tencent RapidJSON at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

An integer underflow in the decimalPosition variable during full-precision float parsing causes an out-of-bounds array access in the GetCachedPowerByIndex() function within include/rapidjson/internal/diyfp.h. When parsing floating-point numbers with the kParseFullPrecisionFlag set, a specially crafted input (such as "1.1" followed by 192 zeros) causes decimalPosition to underflow, resulting in an invalid array index far exceeding the bounds of the kCachedPowers_F array. This enables remote out-of-bounds read without authentication.

Affected products

Tencent RapidJSON 1.1.0

Timeline

2026-10-16: disclosed: Issue #2405 reported on GitHub
2026-11-09: advisory

References

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