CVE-2021-28032: An issue was discovered in the nano_arena crate before 0.5.2 for Rust

Q: How do I fix CVE-2021-28032?

nano arena: upgrade to 0.5.2. Exact commands for each OS are on this page.

Q: Is CVE-2021-28032 being exploited?

CVE-2021-28032 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-28032 affect?

CVE-2021-28032 affects nano arena. Severity is critical (CVSS 9.8). An issue was discovered in the nano_arena crate before 0.5.2 for Rust. There is an aliasing violation in split_at because two mutable references can exist for the same element, if Borrow behaves in certain ways. This can have a resulta

This week

CRITICAL 9.8REMOTEUPGRADE

CVE-2021-28032 is a critical-severity flaw (CVSS 9.8) affecting nano arena. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in the nano_arena crate before 0.5.2 for Rust. There is an aliasing violation in split_at because two mutable references can exist for the same element, if Borrow<Idx> behaves in certain ways. This can have a resultant out-of-bounds write or use-after-free.

Why this priority

Critical severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.5% (top 25%)
CISA exploited list	No
Published	2021-03-05
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: nano arena project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-03-05 09:15 UTCPublished CVE record published
2026-06-17 03:45 UTCUpdated Record last modified

nano arena project nano arena UPGRADE

Affected: < 0.5.2

Fixed in: 0.5.2

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy nano-arena || rpm -q nano-arena || nano-arena --version

2. UPGRADE to 0.5.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade nano-arena

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade nano-arena

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-28032?

nano arena: upgrade to 0.5.2. Exact commands for each OS are on this page.

Is CVE-2021-28032 being exploited?

CVE-2021-28032 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-28032 affect?

CVE-2021-28032 affects nano arena. Severity is critical (CVSS 9.8). An issue was discovered in the nano_arena crate before 0.5.2 for Rust. There is an aliasing violation in split_at because two mutable references can exist for the same element, if Borrow<Idx> behaves in certain ways. This can have a resulta

How urgent is CVE-2021-28032?

Priority 63/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

References

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