CVE-2026-88390: Memory Corruption (CVSS 7.7)

Description

An out-of-bounds write vulnerability in jslGetTokenValueAsString() in Espruino 2v29 (commit bffc6d0) allows crafted JavaScript input containing an overlong token to trigger a one-byte write beyond the JsLex.token buffer in RELEASE/NO_ASSERT builds. The out-of-bounds write corrupts the adjacent tokenValue pointer, resulting in memory corruption and potentially causing application crashes or denial of service.

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CVSS v3.1 Score

7.7

HIGH

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

EPSS — Exploit Prediction

0.0017

Probability of exploitation

0.06%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-787 Out-of-bounds Write

References

Other References

https://github.com/espruino/Espruino/commit/ecd7d43e084ba9aafa8245609347fe0f4383b38c https://github.com/espruino/Espruino/issues/2744 https://github.com/espruino/Espruino/issues/2744

Frequently Asked Questions

What is CVE-2026-88390? +

An out-of-bounds write vulnerability in jslGetTokenValueAsString() in Espruino 2v29 (commit bffc6d0) allows crafted JavaScript input containing an overlong token to trigger a one-byte write beyond the JsLex.token buffer in RELEASE/NO_ASSERT builds. The out-of-bounds write corrupts the adjacent tokenValue pointer, resulting in memory corruption and potentially causing application crashes or denial of service. It has a CVSS v3.1 base score of 7.7 (HIGH).

How severe is CVE-2026-88390? +

CVE-2026-88390 has a CVSS v3.1 score of 7.7 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0017, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-88390? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2026-88390