Skip to main content
Public proof of conceptFix available

CVE-2026-25541

Bytes is vulnerable to integer overflow in BytesMut::reserve

A public proof of concept exists; no exploitation attested.

  • Published2026-02-04
  • Fixed in1.11.1
  • WeaknessCWE-680

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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 capacity. Subsequent APIs such as spare_capacity_mut() then trust this corrupted cap value and may create out-of-bounds slices, leading to UB. This behavior is observable in release builds (integer overflow wraps), whereas debug builds panic due to overflow checks. This issue has been patched in version 1.11.1.

Timeline

dates in UTC
  1. 2026-02-0422:16CVE publishedNVD

Versions per branch

NVD · OSV
Tokio-rs bytes
BranchAffectedFixed in
1.x≥ 1.2.1, < 1.11.11.11.1

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA1 product

As GitHub_M, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • tokio-rs bytes
    Affected
    • = >= 1.2.1, < 1.11.1no fix stated

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-02-04

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • afterburnSUSE:Linux Micro 6.2all versions · fixed in 5.10.0.git73.b97f772-160000.1.1
  • afterburnSUSE:Linux Micro 6.1all versions · fixed in 5.10.0.git73.b97f772-slfo.1.1_1.1
  • afterburnSUSE:Linux Micro 6.0all versions · fixed in 5.10.0.git73.b97f772-1.1
  • afterburnSUSE:Linux Enterprise Server for SAP applications 16.0all versions · fixed in 5.10.0.git73.b97f772-160000.1.1
  • afterburnSUSE:Linux Enterprise Server 16.0all versions · fixed in 5.10.0.git73.b97f772-160000.1.1
  • afterburnSUSE:Linux Enterprise Micro 5.5all versions · fixed in 5.10.0.git73.b97f772-150500.3.6.1
  • afterburnSUSE:Linux Enterprise Micro 5.4all versions · fixed in 5.10.0.git73.b97f772-150400.3.6.1
  • afterburnSUSE:Linux Enterprise Micro 5.3all versions · fixed in 5.10.0.git73.b97f772-150400.3.6.1

193 more package ranges on OSV.dev

Full record on NVD

Fix

  1. Update Tokio-rs bytes to 1.11.1

Advisories and patches

Detection

read 2026-11-01 01:02 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 4.0 vector
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Published
2026-02-04
Last Modified
2026-06-17
NVD status
Analyzed
GitHub Advisory
GHSA-434x-w66g-qw3r

Frequently asked questions

What is CVE-2026-25541?

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 capacity. Subsequent APIs such as spare_capacity_mut() then trust this corrupted cap value and may create out-of-bounds slices, leading to UB. This behavior is observable in release builds (integer overflow wraps), whereas debug builds panic due to overflow checks. This issue has been patched in version 1.11.1.

Is CVE-2026-25541 actively exploited?

A proof-of-concept exploit exists for CVE-2026-25541, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2026-25541?

CVE-2026-25541 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Running bytes? Hear about its next vulnerability

Surveillance reads the versions in your stack — a domain, a lockfile or a list — checks each CVE against the ranges its sources publish, and alerts you when one you run is exploited or enters CISA KEV. A version it cannot read stays « version not verified ».

Get alerts for this productCISA KEV additions, November 2026Search CVEs

No credit card required · No monthly cap on website lookups · 250 API requests/month

Go further

Related vulnerabilities

Same product first, then the same vendor advisory and the same publication week.

Back to CVE Database

Sources for this record