CVE-2025-477742.9LowCWE-691

CVE-2025-47774: Vyper's `slice()` may elide side-effects when output length is 0

vyperlang · vyper

Affected: vyperlang · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.5%probability of exploitation in the next 30 days

41st percentile

050100

Higher than 41% of scored CVEs

2.9LowCVSS 4.0

LowMediumHighCrit.

DescriptionCVE.org

Vyper is the Pythonic Programming Language for the Ethereum Virtual Machine. In versions up to and including 0.4.2rc1, the `slice()` builtin can elide side effects when the output length is 0, and the source bytestring is a builtin (`msg.data` or `<address>.code`). The reason is that for these source locations, the check that `length >= 1` is skipped. The result is that a 0-length bytestring constructed with slice can be passed to `make_byte_array_copier`, which elides evaluation of its source argument when the max length is 0. The impact is that side effects in the `start` argument may be elided when the `length` argument is 0, e.g. `slice(msg.data, self.do_side_effect(), 0)`. The fix in pull request 4645 disallows any invocation of `slice()` with length 0, including for the ad hoc locations discussed in this advisory. The fix is expected to be part of version 0.4.2.

Affected products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

vyperlang · vyper<= 0.4.2rc1

On the Atlas

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Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Insufficient Control Flow Management · Input Validation and Logic
Vendor: vyperlang
Published: May 2025
Band: Unlikely (under 1%), May 2025

CoverageNo articles yet

No CyberSIXT article names CVE-2025-47774 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.