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Not in CISA KEV
HIGH severity

rust-zserio has Unbounded Memory AllocationGHSA-fpf5-4jw8-67x8

HIGHFix: Danaozhong/rust-zserio@57f5fb4

GHSA-fpf5-4jw8-67x8 is a high-severity (CVSS 7.5) remote code execution vulnerability in rust-zserio. A fix is available for rust-zserio — see the affected versions and patch details below.

Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of May 7, 2026 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected
🦀rust-zserio

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

Description

Impact

When deserializing arrays, strings or bytes (blob) types zserio first reads the size of the variable, and then allocates sufficient memory to load data. Since the size is always trusted this can be abused by creating a data file with a large size value, causing the zserio runtime to allocate large amounts of memory.

Patches

Please cherry-pick 57f5fb.

Workarounds

  • Do not accept zserio-encoded messages from non-trusted sources.
  • Allocate a maximum heap amount to rust-zerio to avoid impacting other applications.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🦀crates.iorust-zserioall versions0.5.4cargo update -p rust-zserio --precise 0.5.4

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Fix

    Update rust-zserio to 0.5.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-fpf5-4jw8-67x8 is resolved across your whole dependency graph.

  3. Workarounds

    Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Frequently Asked Questions

### Impact When deserializing arrays, strings or bytes (blob) types zserio first reads the size of the variable, and then allocates sufficient memory to load data. Since the size is always trusted this can be abused by creating a data file with a large size value, causing the zserio runtime to allocate large amounts of memory. ### Patches Please cherry-pick [57f5fb](https://github.com/Danaozhong/rust-zserio/commit/57f5fb4a2a8611d58dbcc1a9221349206dd99c3c). ### Workarounds - Do not accept `zserio`-encoded messages from non-trusted sources. - Allocate a maximum heap amount to `rust-zerio` t
O3 Security · Impact-Aware SCA

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rust-zserio has Unbounded Memory Allocation (High 7.5)