Qiskit SDK C API may trigger an out of bounds write on accessing the unitary matrix with qk_circuit_inst_unitary().
Affects Qiskit SDK v2.4.0 through v2.6.1 when a circuit is left in an allowed but inconsistent state, such as by loading a corrupted QPY file. Fixed in v2.6.2.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in v2.6.2
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. Affected Qiskit SDK versions v2.4.0 through v2.6.1 Circuit must be left in an allowed but inconsistent state by a logic fault, e.g., by loading a corrupted or maliciously constructed QPY file
- 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? →
- 14/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- 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: none
- Automatable: no
- Technical impact: total
Summary
The Qiskit SDK C API, a quantum computing software library, has a flaw in how it handles the unitary matrix when accessed through qk_circuit_inst_unitary(). A local attacker with no login required could exploit this out-of-bounds write to execute arbitrary code.
Read the original description
IBM Qiskit SDK 2.4.0 through 2.6.1 could allow a local attacker to execute arbitrary code due to an out-of-bounds write caused by improper input validation when accessing a corrupted unitary matrix.
cve.now Index
- Exploitation0/40No signal
- Exposure5/25Specific setups only
- Reach?/20Unknown. No tracked technology or package matched
- Severity9.4/10CVSS 8.4, total technical impact per CISA
- No patch0/5No signal
What would change the score
- Would score about 64 if added to CISA KEV
- Would score about 59 if CISA's SSVC rates exploitation active
- Would score about 24 if CISA's SSVC rates it automatable
What to do
Check whether your setup matches what the bug needs.
Affected Qiskit SDK versions v2.4.0 through v2.6.1 Circuit must be left in an allowed but inconsistent state by a logic fault, e.g., by loading a corrupted or maliciously constructed QPY fileUpgrade to a fixed version: v2.6.2.
Timeline
- CVE published
- First seen by cve.now1 day
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- IBM Qiskit SDK
From 2.4.0 · through 2.6.1
Evidence 1
- Patch
Corrections
None so far.
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Questions about CVE-2026-116501
Is CVE-2026-116501 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. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
The C API function qk_circuit_inst_unitary() can perform an out-of-bounds write when accessing a unitary matrix. The advisory says this could lead to arbitrary code execution. It applies when a logic fault has left the circuit in an allowed but inconsistent state, for example after loading a corrupted or maliciously constructed QPY file.Source: ibm.com
Which versions are affected by CVE-2026-116501?
Qiskit SDK: from 2.4.0 through 2.6.1.Source: cve.now feed data
Am I affected, and how do I check?
Qiskit SDK versions v2.4.0 through v2.6.1 are affected, but only when a circuit has been left in an allowed but inconsistent state by a logic fault. Compare the installed Qiskit SDK version with that range to see whether it falls inside it.Source: ibm.com
How do I fix CVE-2026-116501?
Upgrade the Qiskit SDK to v2.6.2, which contains the fix.Source: ibm.com