Blosc c-blosc2 before 3.5.0 Divide-by-Zero via blosc2_schunk_get_slice_buffer()
- Exploited
- Proof of concept public, per CISA
- Fix
- Fixed in 3.5.0
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 3.5.0.
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 22/100 · provisional
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: poc
- Automatable: no
- Technical impact: partial
Summary
The Blosc c-blosc2 compression library, before version 3.5.0, can be crashed when a program reads a slice from a specially crafted Blosc2 frame. An attacker with local access and no login needed can trigger a divide-by-zero that terminates the process, but only if a user takes action to open or read the malicious frame.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original 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.
cve.now Index
- Exploitation15/40CISA rates a proof of concept as public
- Exposure?/25Unknown. No advisory context yet
- Reach?/20Unknown. No tracked technology or package matched
- Severity6.8/10CVSS 6.8
- No patch0/5No signal
What would change the score
- Would score about 62 if added to CISA KEV
- Would score about 57 if CISA's SSVC rates exploitation active
- Would score about 44 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: 3.5.0.
Timeline
- CVE published
- First seen by cve.now
- CISA SSVC assessment
Exploitation: poc · Automatable: no · Technical impact: partial
- Record last updated
Affected versions
- Blosc c-blosc2
fixed in 3.5.0
Evidence 8
- Patch
- Exploit
- Report
- Repository
- Repository
Show all 8 sourcesShow fewer sources
- Repository
- Link
- Link
Corrections
None so far.
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Questions about CVE-2026-122330
Is CVE-2026-122330 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. CISA's SSVC assessment notes a proof of concept exists. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-122330?
c-blosc2: before 3.5.0.Source: cve.now feed data
How do I fix CVE-2026-122330?
Upgrade to a fixed version: 3.5.0.Source: cve.now feed data