Codex

Nullify vs. Codex

Codex Security can scan your code, reproduce issues and draft a patch for review. Nullify runs your product-security program end to end, from proven findings to fixes that get merged. Here's where building it yourself on Codex stops and Nullify takes over.

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Last updated: 2026-11-06 · Based on Codex's public documentation

Always on, not on requestEvery commit and pull request, without anyone opening a session.

Proof before it reaches youFindings validated on reachability, exploitability and business context.

Fixes managed to mergeValidated against your build, then followed through review and CI.

A program, not a promptOwners routed, SLAs escalated, MTTR reported.

Build it yourself or buy it

How Nullify and Codex compare for security

14 capabilities, grouped by what a security program needs: finding risk, fixing and closing it, and running it week after week.

Capability

Codex

Finding risk

Code vulnerability scanning

✓

Threat-model-led scansCodex Security scans connected GitHub repositories in Codex cloud, or local repositories through its plugin and CLI, guided by a threat model you can edit.

✓

Every commit and pull requestAI-native SAST across 16 languages traces untrusted input through real code paths, including business-logic flaws such as IDOR.

Finding validation

–

Reproducers when the environment allowsValidation tries to reproduce each issue. OpenAI notes a failed reproducer doesn't always mean the issue is absent, and validation may need a working build.

✓

Reproducible exploit proofAPI findings are exploited live with request/response evidence, screenshots and video; code findings are validated on reachability, exploitability and business context.

Secrets detection

Not documentedNo live credential verification is described; OpenAI says Codex Security scans application code.

✓

Live credential verificationTests candidate secrets against AWS, GCP, Azure, GitHub, GitLab, Stripe and Slack, with a suspected owner and rotation guidance.

Cloud security

Not documentedCloud accounts aren't in scope; OpenAI says Codex Security scans application code.

✓

AWS, GCP, Azure and Kubernetes auditsEvent-driven, mapped to CIS, PCI-DSS, HIPAA and SOC 2, and traced back to the repo that created each resource.

API pentesting

Not documentedNo continuous testing of running APIs is described.

✓

Continuous AI pentestsMulti-stage exploitation of REST and GraphQL APIs, with each exploit re-reviewed before it's reported; frontends via Bug Hunts.

Fixing and closing risk

Fix generation

✓

Patches you can verifyGenerate a patch, review the diff, then open a draft PR; Verify fix reruns the reproducer and your tests.

✓

Fix PRs validated against your buildA minimal root-cause fix is checked against builds and tests before the pull request opens.

Getting fixes merged

–

Draft PR, then your processOpenAI notes that creating the draft doesn't merge the fix. Follow-through after the PR opens isn't described.

✓

Managed through reviewNullify reads CI output and fixes failures, with at most 3 open fix PRs per repo so reviewers aren't buried.

Ownership and routing

–

Export and track findingsFindings can be exported to your own tools; routing by CODEOWNERS or reviewer capacity isn't described.

✓

Routed to the right ownerCommit author, then CODEOWNERS, then team, with assignment that accounts for each person's open PRs and tickets.

SLA tracking and escalation

Not documentedNo SLA tracking or escalation is described.

✓

Escalated before the SLA slipsStalled security PRs and tickets are escalated in Slack with the risk and SLA stated.

Program reporting

–

Findings across repositoriesCodex cloud tracks open findings and fixes across connected repositories.

✓

MTTR and SLA compliancePlus campaign progress, per-team progress and current finding counts across one prioritized backlog.

Running it

When it runs

◷

Commit monitoring or on demandCodex cloud monitors new commits and is in research preview; the plugin and CLI run when you start them.

◷

ContinuouslyScans every default-branch commit and pull request; cloud audits run when your environment changes.

Source control

◇

GitHub for Codex cloudThe CLI's CI guides cover GitHub Actions and GitLab CI/CD.

◇

GitHub, GitLab, Bitbucket or Azure DevOpsA dedicated enterprise tenant with scoped, least-privilege access.

Cost model

Your token usageRepository and continuous scans are billed on token usage at your plan's rates; eligible accounts get $500 in free scanning credits.

Outcome-basedPriced against the security work Nullify performs, not per seat or per token.

Who runs it

◎

Your teamSomeone owns the threat model, triage, patch review and follow-up on every draft PR.

◎

NullifyYour team sets the guardrails and approves every merge.

✓Supported –Limited or partial ×Not offered or not documented

4 areas where Nullify goes further than Codex

Coverage beyond application code

Nullify

Nullify covers code, dependencies, leaked secrets with live verification, cloud configuration across AWS, GCP, Azure and Kubernetes, and continuous API pentests in one backlog.

CCodex

Codex Security scans application code. Secrets verification, cloud posture and dynamic testing need other tools.

Proof before it reaches your team

Nullify

API findings are exploited live with request/response evidence, screenshots and video. Code findings are validated on reachability, exploitability and business context, so only real risk makes the list.

CCodex

Codex tries to reproduce each finding when the environment allows. OpenAI notes a scan with no findings can still miss vulnerabilities.

Fixes that get merged

Nullify

Fixes are validated against your build and tests before the PR opens. If CI fails, Nullify reads the logs and fixes it, with no more than 3 open fix PRs per repo.

CCodex

Codex drafts a patch and can open a draft PR after you review the diff. Getting it through review and CI is your team's job.

A program that reaches closure

Nullify

One prioritized backlog scored 0–100, campaigns toward a target, owners routed by CODEOWNERS and capacity, Slack escalation before the SLA slips, and MTTR reporting.

CCodex

Codex cloud tracks open findings and fixes. Routing, SLAs and program reporting are whatever your team builds around it.

Use both

Your developers keep their coding agent while Nullify runs the security program

Keep Codex for writing software

Your developers keep using Codex to write and review code. Nullify takes the security program off their plate without changing how they build.

Let Nullify close the last mile

Nullify proves what's real, writes fixes validated against your build, routes each one to an owner with time to review it, and escalates before the SLA slips. Your team approves every merge.

FAQ

Questions teams ask before building their own security harness

Can't we build this ourselves on Codex?

You can get a long way: Codex Security scans your code, tries to reproduce findings and drafts patches. The hard part is everything after the finding: covering secrets, cloud and running APIs, routing each fix to an owner, getting PRs merged and reporting MTTR against your SLAs. Nullify does that work, so your engineers don't maintain a harness.

Does Nullify replace Codex?

No. Developers keep using Codex to write software. Nullify runs the security program alongside it, from detection through to merge-ready fixes.

Does Nullify merge fixes automatically?

No. Nullify is automated through merge readiness and human-controlled at merge. Your team approves every merge.

How does pricing compare?

Codex Security scans are billed on token usage at your plan's rates. Nullify is outcome-based, priced against the security work it performs rather than per seat or per token.

Reduce your vulnerability backlog and lower your MTTR

The AI harness that finds, proves and fixes vulnerabilities across your codebase. Watch Nullify find, prove and fix a vulnerability in your own stack.

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Sources. Codex details on this page come from its maker's own documentation, checked on 2026-11-06. Features and pricing change, so confirm current terms with the vendor.