CVE-2026-25541: Bytes is a utility library for working with bytes

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HIGH 7.5REMOTEUPGRADE

CVE-2026-25541 is a high-severity flaw (CVSS 7.5) affecting bytes. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Bytes is a utility library for working with bytes. From version 1.2.1 to before 1.11.1, Bytes is vulnerable to integer overflow in BytesMut::reserve. In the unique reclaim path of BytesMut::reserve, if the condition "v_capacity >= new_cap + offset" uses an unchecked addition. When new_cap + offset overflows usize in release builds, this condition may incorrectly pass, causing self.cap to be set to a value that exceeds the actual allocated capacit

Why this priority

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

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.6% (top 51%)
CISA exploited list	No
Weakness	CWE-680
Published	2026-02-04
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: tokio-rs

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

Am I affected?

Timeline

2026-02-04 22:16 UTCPublished CVE record published
2026-06-17 10:24 UTCUpdated Record last modified

tokio-rs bytes UPGRADE

Affected: >= 1.2.1 and < 1.11.1

Fixed in: 1.11.1

Safe to downgrade to: a release before 1.2.1

1. Check installed version

apt-cache policy bytes || rpm -q bytes || bytes --version

2. UPGRADE to 1.11.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade bytes

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade bytes

Note

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

3. If no update is available yet, DOWNGRADE to a release before 1.2.1 (Debian / Ubuntu)

apt-cache madison bytes sudo apt install bytes=<VERSION_BEFORE_1.2.1> sudo apt-mark hold bytes

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list bytes sudo dnf downgrade bytes-<VERSION_BEFORE_1.2.1> sudo dnf versionlock add bytes

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

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-2026-25541?

bytes: upgrade to 1.11.1. Exact commands for each OS are on this page.

Is CVE-2026-25541 being exploited?

CVE-2026-25541 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-2026-25541 affect?

CVE-2026-25541 affects bytes. Severity is high (CVSS 7.5). Bytes is a utility library for working with bytes. From version 1.2.1 to before 1.11.1, Bytes is vulnerable to integer overflow in BytesMut::reserve. In the unique reclaim path of BytesMut::reserve, if the condition "v_capacity >= new_cap +

How urgent is CVE-2026-25541?

Priority 49/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

References

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