CVE-2024-45056: zksolc is a Solidity compiler for ZKsync. All LLVM versions since 2015 fold `(xor (shl 1, x), -1)` to `(rotl ~1, x)` if run with optimizations enabled...

Description

zksolc is a Solidity compiler for ZKsync. All LLVM versions since 2015 fold `(xor (shl 1, x), -1)` to `(rotl ~1, x)` if run with optimizations enabled. Here `~1` is generated as an unsigned 64 bits number (`2^64-1`). This number is zero-extended to 256 bits on EraVM target while it should have been sign-extended. Thus instead of producing `roti 2^256 - 1, x` the compiler produces `rotl 2^64 - 1, x`. Analysis has shown that no contracts were affected by the date of publishing this advisory. This issue has been addressed in version 1.5.3. Users are advised to upgrade and redeploy all contracts. There are no known workarounds for this vulnerability.

Metrics

CVSS 3.1

5.9/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS Probability

0.40%

32.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Matter-Labs	Zksolc	< 1.5.3

References

Timeline

Published: Aug 29, 2024
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2024-45056?

zksolc is a Solidity compiler for ZKsync. All LLVM versions since 2015 fold `(xor (shl 1, x), -1)` to `(rotl ~1, x)` if run with optimizations enabled. Here `~1` is generated as an unsigned 64 bits number (`2^64-1`). This number is zero-extended to 256 bits on EraVM target while it should have been sign-extended. Thus instead of producing `roti 2^256 - 1, x` the compiler produces `rotl 2^64 - 1, x`. Analysis has shown that no contracts were affected by the date of publishing this advisory. This issue has been addressed in version 1.5.3. Users are advised to upgrade and redeploy all contracts. There are no known workarounds for this vulnerability.

How severe is CVE-2024-45056?

CVE-2024-45056 has a CVSS score of 5.9/10 (MEDIUM severity). The EPSS model estimates a 0.40% probability of exploitation in the next 30 days.

How do I fix CVE-2024-45056?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.