CVE-2026-122330: Blosc c-blosc2 · Divide By Zero
Affects Blosc c-blosc2Source CVE Database V5
Not known to be exploited · CVSS 6.8 Medium : upgrade to 3.5.0 when convenient.
Data as of 5 Nov 2026, 15:34 UTC
Thin evidence
One scorer or none| CNA (VulnCheck) | CVSS 4.0 | 6.8 |
|---|---|---|
| CNA (VulnCheck) | CVSS 3.1 | 5.5 |
- Patch
- Available – fixed in 3.5.0
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 5 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.
What to do
Upgrade Blosc c-blosc2 to 3.5.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Bloscc-blosc2 | Affected
| Fixed in
|
GitHubc-blosc2pkg:github/c-blosc2Other threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
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.
References
- github.com/Blosc/c-blosc2/issues/834 (opens in a new tab)
- github.com/Blosc/c-blosc2/commit/4fff1787408d94b895c6f9cb50f7925ad5919052 (opens in a new tab)
- github.com/Blosc/c-blosc2/blob/v3.4.1/blosc/schunk.c (opens in a new tab)
- github.com/Blosc/c-blosc2/blob/v3.4.1/blosc/frame.c (opens in a new tab)
- hackmd.io/@haindpwn/c-blosc2-schunk-slice-divide-by-zero (opens in a new tab)
- github.com/Blosc/c-blosc2 (opens in a new tab)
- vulncheck.com/advisories/blosc-c-blosc2-before-3.5.0-divide-by-zero-via-blosc2-schunk-get-slice-buffer (opens in a new tab)