CVE-2026-25541
Integer Overflow in BytesMut::reserve Causes Out-of-Bounds Access
Publication date: 2026-02-04
Last updated on: 2026-02-27
Assigner: GitHub, Inc.
Description
Description
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| tokio-rs | bytes | From 1.2.1 (inc) to 1.11.1 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-680 | The product performs a calculation to determine how much memory to allocate, but an integer overflow can occur that causes less memory to be allocated than expected, leading to a buffer overflow. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability exists in the Bytes utility library versions from 1.2.1 up to but not including 1.11.1. It involves an integer overflow in the BytesMut::reserve function. Specifically, in a unique reclaim path, an unchecked addition of new_cap and offset can overflow the usize type in release builds. When this overflow occurs, a condition meant to check capacity incorrectly passes, causing the internal capacity (self.cap) to be set to a value larger than the actual allocated memory.
As a result, subsequent API calls like spare_capacity_mut() rely on this corrupted capacity value and may create out-of-bounds slices, leading to undefined behavior (UB). This issue manifests in release builds where integer overflow wraps around, while debug builds detect the overflow and panic. The vulnerability was fixed in version 1.11.1.
How can this vulnerability impact me? :
The vulnerability can lead to undefined behavior due to out-of-bounds memory access caused by corrupted capacity values. This can potentially result in memory corruption, crashes, or other unpredictable behavior in applications using the affected Bytes library versions.
Since the issue arises from integer overflow in release builds, it may be harder to detect during development but can cause serious runtime errors in production environments.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
The vulnerability in Bytes library versions from 1.2.1 to before 1.11.1 has been patched in version 1.11.1.
To mitigate this vulnerability, you should upgrade the Bytes library to version 1.11.1 or later.