CVE-2026-33666

Description

Zserio is a framework for serializing structured data with a compact and efficient way with low overhead. Prior to 2.18.1, in BitStreamReader.h readBytes() / readString(), the setBitPosition() bounds check receives the overflowed value and is completely bypassed. The code then reads len bytes (512 MB) from a buffer that is only a few bytes long, causing a segmentation fault. This vulnerability is fixed in 2.18.1.

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CVSS v3.1 Score

7.5

HIGH

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

EPSS — Exploit Prediction

0.0006

Probability of exploitation

0.17%

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-190 Integer Overflow

Affected Products

Vendor	Product	Versions
nds-association	zserio	< 2.18.1

References

Advisories & Patches

https://github.com/ndsev/zserio/security/advisories/GHSA-fjwv-6wcr-vqwj https://github.com/ndsev/zserio/security/advisories/GHSA-fjwv-6wcr-vqwj

Exploits

https://github.com/ndsev/zserio/security/advisories/GHSA-fjwv-6wcr-vqwj https://github.com/ndsev/zserio/security/advisories/GHSA-fjwv-6wcr-vqwj

Frequently Asked Questions

What is CVE-2026-33666? +

Zserio is a framework for serializing structured data with a compact and efficient way with low overhead. Prior to 2.18.1, in BitStreamReader.h readBytes() / readString(), the setBitPosition() bounds check receives the overflowed value and is completely bypassed. The code then reads len bytes (512 MB) from a buffer that is only a few bytes long, causing a segmentation fault. This vulnerability is fixed in 2.18.1. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-33666? +

CVE-2026-33666 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0006, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-33666? +

CVE-2026-33666 affects products from nds-association, specifically: zserio. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-33666? +

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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