Vulnerability · Published Nov 5, 2026 · Assigned by VulnCheck
CVE-2026-122330Blosc c-blosc2 before 3.5.0 Divide-by-Zero via blosc2_schunk_get_slice_buffer()
Medium 5.5
In plain English
A medium-severity security flaw in c-blosc2 from Blosc. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 15% of all known vulnerabilities).
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu:24.04:LTS | c-blosc2 | no fix listed | UBUNTU-CVE-2026-122330 |
| Ubuntu:26.04:LTS | c-blosc2 | no fix listed | UBUNTU-CVE-2026-122330 |
| Ubuntu:26.10 | c-blosc2 | no fix listed | UBUNTU-CVE-2026-122330 |
Affected products (as reported)
Weakness: CWE-369 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
References
- https://github.com/Blosc/c-blosc2/issues/834 issue-tracking
- https://github.com/Blosc/c-blosc2/commit/4fff1787408d94b895c6f9cb50f7925ad5919052 patch
- https://github.com/Blosc/c-blosc2/blob/v3.4.1/blosc/schunk.c#L1662-L1700 technical-description
- https://github.com/Blosc/c-blosc2/blob/v3.4.1/blosc/frame.c#L1214-L1227 technical-description
- https://hackmd.io/@haindpwn/c-blosc2-schunk-slice-divide-by-zero third-party-advisory
- https://github.com/Blosc/c-blosc2 product
- VulnCheck Advisory: Blosc c-blosc2 before 3.5.0 Divide-by-Zero via blosc2_schunk_get_slice_buffer() third-party-advisory
- https://hackmd.io/@haindpwn/cve-2026-122330-c-blosc2-schunk-slice-divide-by-zero exploit