OPA Compiler: Bypass of WithUnsafeBuiltins using `with` keyword to mock functions
Open Policy Agent (OPA) is an open source, general-purpose policy engine. The Rego compiler provides a (deprecated) `WithUnsafeBuiltins` function, which allows users to provide a set of built-in functions that should be deemed unsafe — and as such rejected — by the compiler if encountered in the policy compilation stage. A bypass of this protection has been found, where the use of the `with` keyword to mock such a built-in function (a feature introduced in OPA v0.40.0), isn’t taken into account by `WithUnsafeBuiltins`. Multiple conditions need to be met in order to create an adverse effect. Version 0.43.1 contains a patch for this issue. As a workaround, avoid using the `WithUnsafeBuiltins` function and use the `capabilities` feature instead.
- Published
- Sep 8, 2022
- Updated
- Jun 17, 2026
- EPSS
- 1.6% · 75th percentile
- CWE
- CWE-20
Sign in to follow · You’ll be notified if a followed record enters KEV, gets an exploit or is updated.
Report tools
Action score
39
Monitor
Low priority for now.
- CVSS
- 39 / 40 · 9.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 1.6%
CISA SSVC decision
- Exploitation
- proof of concept
- Automatable
- no
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- 9.8
- CNA · GitHub_M
- 7.4
- 2.4 point gap
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpAffected systems
| Vendor | Product | CPE |
|---|---|---|
| openpolicyagent | open policy agent | cpe:2.3:a:openpolicyagent:open_policy_agent |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- openpolicyagent open policy agent0.40.0 and later · before 0.43.1
Versions reported by the vendor
Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.
open-policy-agent opa
- >= 0.40.0, < 0.43.1affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Go | github.com/open-policy-agent/opa | from 0.40.0 · before 0.43.1 | 0.43.1 |
| Go | github.com/open-policy-agent/opa | from 0.40.0 · before 0.44.0 | 0.44.0 |
Same product
openpolicyagent: all recordsOther highest-scoring records for the same primary product.
- CVE-2022-33082An issue in the AST parser (ast/compile.go) of Open Policy Agent v0.10.2 allows attackers to cause a Denial of Service (DoS) via a crafted i31Monitor
- CVE-2022-28946An issue in the component ast/parser.go of Open Policy Agent v0.39.0 causes the application to incorrectly interpret every expression, causi30Monitor
- CVE-2024-8260OPA SMB Force-Authentication29Monitor
- CVE-2022-23628Array literal misordering in github.com/open-policy-agent/opa21Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Go:github.com/open-policy-agent/opa | 0.43.1 | Package registry (OSV) |
| Go:github.com/open-policy-agent/opa | 0.44.0 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-20 · Improper Input ValidationCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Buffer Overflow via Environment VariablesCAPEC-10likelihood: High · High
- Server Side Include (SSI) InjectionCAPEC-101likelihood: High · High
- Cross Zone ScriptingCAPEC-104likelihood: Medium · High
- Command Line Execution through SQL InjectionCAPEC-108likelihood: Low · Very High
- Object Relational Mapping InjectionCAPEC-109likelihood: Low · High
- SQL Injection through SOAP Parameter TamperingCAPEC-110likelihood: High · Very High
- Double EncodingCAPEC-120likelihood: Low · Medium
- Subverting Environment Variable ValuesCAPEC-13likelihood: High · Very High
ATT&CK techniques
- Obfuscated Files or InformationT1027
- Masquerading: Invalid Code SignatureT1036.001
- Steal Web Session CookieT1539
- Subvert Trust Controls: Code SigningT1553.002
- Impair Defenses:Impair Command History LoggingT1562.003
- Hijack Execution Flow:Dynamic Linker HijackingT1574.006
- Hijack Execution Flow:Path Interception by PATH Environment VariableT1574.007
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- github.com/open-policy-agent/opa/commit/25a597bc3f4985162e7f65f9c36599f4f8f55823
- github.com/open-policy-agent/opa/commit/3e8c754ed007b22393cf65e48751ad9f6457fee8
- github.com/open-policy-agent/opa/releases/tag/v0.43.1
Vendor advisories and official records. Exploit/PoC links are deliberately left out.