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VulnerabilityPublished

CVE-2026-122330: Blosc c-blosc2 · Divide By Zero

Affects Blosc c-blosc2Source CVE Database V5

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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

CVSS 4.0 base score
6.8Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (VulnCheck)CVSS 4.06.8
CNA (VulnCheck)CVSS 3.15.5
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:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 5 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

ProductAffectedFixed in
Bloscc-blosc2Affected
  • <3.5.0
Fixed in
  • 3.5.0
GitHubc-blosc2pkg:github/c-blosc2Other threatsAffected
  • <3.5.0
Fixed in
  • 3.5.0

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

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