CVE-2026-122330 (CVSS 5.5)

Description

Blosc c-blosc2 before 3.5.0 contains a divide-by-zero vulnerability in blosc2_schunk_get_slice_buffer() in blosc/schunk.c that allows attackers to crash applications by supplying crafted frames with unchecked zero chunksize or blocksize values. Attackers can provide a malicious Blosc2 frame opened via blosc2_schunk_open() or blosc2_schunk_from_buffer() and read as a slice, raising SIGFPE and terminating the process.

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CVSS v3.1 Score

5.5

MEDIUM

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

EPSS — Exploit Prediction

0.0024

Probability of exploitation

0.15%

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-369 CWE-369

References

Other References

https://github.com/Blosc/c-blosc2 https://github.com/Blosc/c-blosc2/blob/v3.4.1/blosc/frame.c#L1214-L1227 https://github.com/Blosc/c-blosc2/blob/v3.4.1/blosc/schunk.c#L1662-L1700 https://github.com/Blosc/c-blosc2/commit/4fff1787408d94b895c6f9cb50f7925ad5919052 https://github.com/Blosc/c-blosc2/issues/834 https://hackmd.io/@haindpwn/c-blosc2-schunk-slice-divide-by-zero https://www.vulncheck.com/advisories/blosc-c-blosc2-before-3.5.0-divide-by-zero-via-blosc2-schunk-get-slice-buffer https://hackmd.io/@haindpwn/cve-2026-122330-c-blosc2-schunk-slice-divide-by-zero

Frequently Asked Questions

What is CVE-2026-122330? +

Blosc c-blosc2 before 3.5.0 contains a divide-by-zero vulnerability in blosc2_schunk_get_slice_buffer() in blosc/schunk.c that allows attackers to crash applications by supplying crafted frames with unchecked zero chunksize or blocksize values. Attackers can provide a malicious Blosc2 frame opened via blosc2_schunk_open() or blosc2_schunk_from_buffer() and read as a slice, raising SIGFPE and terminating the process. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2026-122330? +

CVE-2026-122330 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0024, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-122330? +

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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