CVE-2025-59941

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.

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.

• 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.

CVE-2025-59941 has a CVSS score of 5.9 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.8.9); upgrading removes the vulnerable code path.

Kodem intelligence

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.

1. What is CVE-2025-59941? CVE-2025-59941 is a medium-severity security vulnerability in github.com/filecoin-project/go-f3 (go), affecting versions < 0.8.9. It is fixed in 0.8.9.
2. How severe is CVE-2025-59941? CVE-2025-59941 has a CVSS score of 5.9 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/filecoin-project/go-f3 are affected by CVE-2025-59941? github.com/filecoin-project/go-f3 (go) versions < 0.8.9 is affected.
4. Is there a fix for CVE-2025-59941? Yes. CVE-2025-59941 is fixed in 0.8.9. Upgrade to this version or later.
5. Is CVE-2025-59941 exploitable, and should I be worried? Whether CVE-2025-59941 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2025-59941 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2025-59941? Upgrade github.com/filecoin-project/go-f3 to 0.8.9 or later.