How severe is CVE-2025-59941?

CVE-2025-59941 has a CVSS score of 5.9/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2025-59941?

CVE-2025-59941 affects the following packages: github.com/filecoin-project/go-f3 (Go). Ecosystems affected: Go.

How do I fix CVE-2025-59941?

Update github.com/filecoin-project/go-f3 to 0.8.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-59941 is resolved across your whole dependency graph.

How do I detect CVE-2025-59941 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/filecoin-project/go-f3, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2025-59941 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2025-59941 actively exploited in the wild?

No public exploit code has been indexed for CVE-2025-59941 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2025-59941?

CVE-2025-59941 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 16th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2025-59941?

CVE-2025-59941 is classified as CWE-305 (CWE-305). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2025-59941 published, and has it been updated?

CVE-2025-59941 was published on September 29, 2025 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹

🐹 Go

Not in CISA KEV

MEDIUM severity

CVE-2025-59941 — go-f3

MEDIUMFix: filecoin-project/go-f3@76fff18

CVE-2025-59941 is a medium-severity (CVSS 5.9) CWE-305 vulnerability in github.com/filecoin-project/go-f3. A fix is available for github.com/filecoin-project/go-f3 — see the affected versions and patch details below.

go-f3 is Vulnerable to Cached Justification Verification Bypass

Also known asGHSA-7pq9-rf9p-wcrfGO-2025-3989

Published

Sep 29, 2025

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2025-59941.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs16th percentile — riskier than 16% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

🐹github.com/filecoin-project/go-f3

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

A vulnerability exists in go-f3's justification verification caching mechanism where verification results are cached without properly considering the context of the message. An attacker can bypass justification verification by:

First submitting a valid message with a correct justification
Then reusing the same cached justification in contexts where it would normally be invalid

This occurs because the cached verification does not properly validate the relationship between the justification and the specific message context it's being used with.

Impact

Potential consensus integrity issues through invalid justification acceptance
Could affect network liveness if exploited systematically
May allow malicious actors to influence consensus decisions with invalid justifications
Requires significant power (350+ TiB due to power table rounding) to meaningfully exploit
It would also be difficult to exploit in a synchronised fashion, such that >1/3 of the network goes down at one time. This isn't a one-msg panic, where you can spam it and bring everyone down, because every node will have a different amount of memory andmany SPs also run redundant lotus nodes.

Patches

The fix was merged and released with go-f3 0.8.9. All node software (Lotus, Forest, Venus) are using a patched version of go-f3 with their updates for the nv27 network upgrade.

Workarounds

The are no immediate workarounds available. Nodes should upgrade to the patched version, which they will have done if participating in nv27 on Filecoin mainnet.

Credits

The bug was reported by @lgprbs via our bug bounty program. Thank you for the contributions.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/filecoin-project/go-f3`	all versions	0.8.9`go get github.com/filecoin-project/go-f3@v0.8.9`

Affected Products

1 product · 1 configurations

Application

go-f3filecoin

< 0.8.9

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/filecoin-project/go-f3, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/filecoin-project/go-f3 to 0.8.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-59941 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### Description A vulnerability exists in go-f3's justification verification caching mechanism where verification results are cached without properly considering the context of the message. An attacker can bypass justification verification by: 1. First submitting a valid message with a correct justification 2. Then reusing the same cached justification in contexts where it would normally be invalid This occurs because the cached verification does not properly validate the relationship between the justification and the specific message context it's being used with. ### Impact - Potential cons