Cybersecurity · head to head
Cosign vs Falco
Cosign
Cybersecurity
Signs and verifies container images and artifacts, with or without managing keys
- From
- Free
- Rated
- -
Falco
Cybersecurity
CNCF-graduated runtime threat detection for Linux and Kubernetes using eBPF
- From
- Free
- Rated
- -
The short version
- Each has a real cost: Cosign keyless signing inherits every weakness of the identity provider behind it. Sigstore’s own threat model states that if an identity provider is compromised, Sigstore will issue certificates to those identities, so a compromised account produces perfectly valid signatures.; Falco falco detects and alerts but does not block; stopping an attack requires wiring up Falco Talon or your own response tooling, so out of the box a confirmed detection still means a human intervening after the fact.
- They diverge on capability: Cosign covers Keyless signing, Falco covers eBPF kernel instrumentation.
- Prices and features above were last checked on 31 August 2026.
Where they differ
Only the attributes on which Cosign and Falco actually diverge.
Identical on both: starting price (Free), pricing model (Open source, no licence fee), free tier (Yes), user rating (Not yet rated), category (Cybersecurity).
What each one covers
Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.
Only in Cosign
- Keyless signing
- Key and KMS signing
- Registry-native storage
- In-toto attestations
- Offline verification
- Trusted root and signing config
Only in Falco
- eBPF kernel instrumentation
- System call rules engine
- Container and Kubernetes context
- Default rule set
- Falcosidekick
- Falco Talon
- Plugins framework
- DaemonSet deployment
What people use each for
The jobs each tool is most often brought in to do.
Cosign
- Signing container images in a build pipeline without managing long-lived private keysnot Falco
- Attaching a signed bill of materials to a release so consumers can verify its provenancenot Falco
- Meeting a customer or regulatory requirement for signed artifactsnot Falco
- Verifying third-party images before they enter an internal registrynot Falco
Falco
- A platform team that needs to know when a shell is opened inside a production container, which image scanning cannot detect because it happens at runtimenot Cosign
- A regulated business required to evidence host and container intrusion detection on Kubernetes nodes for an auditnot Cosign
- A security team wanting a vendor-neutral detection layer whose rules they can read and modify rather than a black-box agentnot Cosign
- A cluster where a compromised dependency might write to sensitive paths or open unexpected outbound connections, and only kernel-level visibility will catch itnot Cosign
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
Cosign
- Keyless signing inherits every weakness of the identity provider behind it. Sigstore’s own threat model states that if an identity provider is compromised, Sigstore will issue certificates to those identities, so a compromised account produces perfectly valid signatures.
- A signature proves who signed, never whether they should have. The documentation is explicit that Sigstore cannot determine authorisation, so every consumer must write and maintain their own identity and issuer policy or verification means nothing.
- Nothing is enforced without an admission controller. Signing changes what you can prove, not what runs, and the official policy controller has a small maintainer base for a component sitting in a cluster admission path.
- Upgrades break pipelines. Version 3 changed defaults, version 4 is announced as removing legacy functionality and roughly half the command line flags, and two official client libraries still lacked support for the new log format as of mid 2026.
- Signatures do not expire. An artifact signed before a maintainer account was compromised and one signed after are indistinguishable unless somebody is actively monitoring the transparency log, and almost nobody is.
Falco
- Falco detects and alerts but does not block; stopping an attack requires wiring up Falco Talon or your own response tooling, so out of the box a confirmed detection still means a human intervening after the fact.
- The default rule set is noisy in real clusters and generates a large volume of benign matches from normal operational activity; without weeks of tuning, alert fatigue sets in and the team stops reading the feed, which is the usual failure mode.
- There is no storage, console, search or case management in the project, so a working detection capability means also running Falcosidekick, an event store, a dashboard and alert routing, all of which you build, host and maintain.
- The modern eBPF driver requires kernel 5.8 or later; older hosts fall back to the legacy probe or the kernel module, which brings driver-building against kernel headers and the operational fragility that comes with it on every kernel upgrade.
- Per-node syscall instrumentation carries measurable CPU overhead on busy hosts, and the cost scales with syscall volume rather than with cluster size, so the noisiest and most performance-sensitive workloads are exactly the ones that feel it most.
Pricing, plan by plan
Cosign
Free- CosignFree
- Apache-2.0
- Public Sigstore infrastructure free to use
- No usage limits published
Falco
Free- Falco (open source)Free
- Apache 2.0 licence, CNCF graduated project
- eBPF and kernel module drivers
- Full rules engine and default rule set
Which should you pick?
Choose Cosign if
- You need keyless signing.
- You want to start without paying.
- You work on macOS, Linux, Windows, Docker.
- You also want key and kms signing.
Choose Falco if
- You need ebpf kernel instrumentation.
- You want to start without paying.
- You work on Linux, Kubernetes, Self-hosted.
- You also want system call rules engine.
Questions people ask
- Is Cosign or Falco better?
- Neither clearly leads. Cosign starts at Free and Falco at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, Cosign or Falco?
- Cosign starts at Free and Falco at Free.
- Does Cosign or Falco run on more platforms?
- Cosign runs on macOS, Linux, Windows, Docker. Falco runs on Linux, Kubernetes, Self-hosted.
- Can I use Cosign for free?
- Both have a free tier, so you can try either at no cost before committing.
- What is Cosign best used for?
- Cosign is most often used for signing container images in a build pipeline without managing long-lived private keys, attaching a signed bill of materials to a release so consumers can verify its provenance, meeting a customer or regulatory requirement for signed artifacts, verifying third-party images before they enter an internal registry. Of those, signing container images in a build pipeline without managing long-lived private keys and attaching a signed bill of materials to a release so consumers can verify its provenance are not what Falco is typically brought in for.
- What can Cosign do that Falco cannot?
- Cosign covers Keyless signing, Key and KMS signing, Registry-native storage, In-toto attestations. Falco covers eBPF kernel instrumentation, System call rules engine, Container and Kubernetes context, Default rule set.
Answered from the vendors’ own pages
Cosign: Does Cosign tell me if an image is vulnerable?
No. It has no vulnerability knowledge whatsoever. It can carry an SBOM as a signed attestation but never reads it. Pair it with a scanner.
Falco: Does Falco block attacks?
No. It detects and emits events. Response requires Falco Talon or your own automation on top.
Cosign: Is signing alone enough?
No. Verification is a command somebody runs. Without an admission controller enforcing it, an unsigned image still runs.
Falco: Is Falco owned by Sysdig?
Sysdig created and open sourced it, but it graduated within the CNCF in February 2024, so governance sits with the foundation rather than the vendor.
Cosign: What does a bare cosign verify actually prove?
Very little. Without a pinned certificate identity and OIDC issuer, it accepts a valid signature from any identity at all.
Falco: What does it cost?
The project is Apache 2.0 with no licence fee. The cost is the storage, routing, tuning and staff time needed to make its output useful.
Cosign: What is the risk of keyless signing?
Your OIDC provider becomes the root of trust. Compromise of that account yields genuine, verifiable signatures, so account security is the control that matters.
Falco: What kernel version do I need?
Kernel 5.8 or later for the default modern eBPF driver. Older hosts need the legacy eBPF probe or the kernel module.
Cosign: Should we expect breaking changes?
Yes. Version 4 is announced to remove roughly half the flags, and a post-quantum migration is named as a further breaking change after that.
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