Vulnerability in Blosc C-Blosc2
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/Blosc/c-blosc2 (product)
- github.com/Blosc/c-blosc2/blob/v3.4.1/blosc/frame.c (technical-description)
- github.com/Blosc/c-blosc2/blob/v3.4.1/blosc/schunk.c (technical-description)
- github.com/Blosc/c-blosc2/commit/4fff1787408d94b895c6f9cb50f7925ad5919052 (patch)
- github.com/Blosc/c-blosc2/issues/834 (issue-tracking)
- hackmd.io/@haindpwn/c-blosc2-schunk-slice-divide-by-zero (third-party-advisory)
- VulnCheck Advisory: Blosc c-blosc2 before 3.5.0 Divide-by-Zero via blosc2_schunk_get_slice_buffer() (third-party-advisory)
- 134c704f-9b21-4f2e-91b3-4a467353bcc0
Frequently asked questions
- What is CVE-2026-122330?
- CVE-2026-122330 is a medium-severity vulnerability in Blosc C-Blosc2, classified under Divide By Zero. CVSS score: 5.5/10. Published 2026-11-05.
- How severe is CVE-2026-122330?
- Medium severity. CVSS v3 base score is 5.5 out of 10.