CVE-2025-61588: risc0 vulnerable to arbitrary code execution in guest via memory safety failure in `sys_read`

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.5%, percentile 39: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 39% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes risc0-zkvm-platform (crates.io (Rust)) < 2.1.0, fixed in 2.1.0; risc0-zkos-v1compat (crates.io (Rust)) < 2.1.0, fixed in 2.1.0; risc0-aggregation (crates.io (Rust)) < 0.9, fixed in 0.9; risc0-zkvm (crates.io (Rust)) < 2.3.2, fixed in 2.3.2. Check your lockfile, including transitive dependencies.

What it is

RISC Zero is a zero-knowledge verifiable general computing platform based on zk-STARKs and the RISC-V microarchitecture. In versions 2.0.2 and below of risc0-zkvm-platform, when the zkVM guest calls sysread, the host is able to use a crafted response to write to an arbitrary memory location in the guest. This capability can be leveraged to execute arbitrary code within the guest. As sysread is the mechanism by which input is requested by the guest, all guest programs built with the affected versions are vulnerable. This critically compromises the soundness guarantees of the guest program. Other affected packages include risc0-aggregation versions below 0.9, risc0-zkos-v1compat below 2.1.0, risc0-zkvm versions between 3.0.0-rc.1 and 3.0.1. This issue has been fixed in the following versions: risc0-zkvm-platform 2.1.0, risc0-zkos-v1compat 2.1.0, risc0-aggregation 0.9, and risc0-zkvm 2.3.2 and 3.0.3.

From the GitHub advisory

Arbitrary code execution in guest via memory safety failure in sysread

In affected versions of risc0-zkvm-platform, when the zkVM guest calls sysread, the host is able to use a crafted response to write to an arbitrary memory location in the guest. This capability can be leveraged to execute arbitrary code within the guest. As sysread is the mechanism by which input is requested by the guest, all guest programs built with the affected versions are vulnerable. This critically compromises the soundness guarantees of the guest program.

A fix was applied in \#3351. The vulnerable pointer arithmetic was removed, and replaced with a simplified implementation in the v1compat kernel which uses Rust’s slice functions to guarantee memory safety.

The fix has been released as part of risc0-zkvm versions 2.3.2 and 3.0.3. All prior versions are affected.

Remediation

Weakness type: CWE-94.

Product: risc0-zkvm-platform (crates.io (Rust)) · Assigned by: GitHub_M · Published: 2025-10-01

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: none
• Privileges required: none (no login)
• User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.46% probability of exploitation activity in the next 30 days; percentile 39.

Timeline

• 2025-10-01 — CVE record published by GitHub_M
• 2025-10-01 — GitHub-reviewed advisory GHSA-jqq4-c7wq-36h7 published (critical)
• 2025-10-02 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-jqq4-c7wq-36h7 github.com
2. CVE.org record CVE-2025-61588 cve.org
3. NVD entry CVE-2025-61588 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com

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