Listen to this Post
The vulnerability arises from a soundness issue in the `IterMut` iterator implementation within an affected Rust crate. When `IterMut::next` or `IterMut::next_back` methods are invoked, they dereference an internal node pointer to temporarily create an exclusive reference (&mut) to the key. This action invalidates the shared pointer (&) held by the internal HashMap, which violates Stacked Borrows rules. Stacked Borrows is a foundational model for defining aliasing and memory safety in Rust, ensuring that references adhere to strict borrowing protocols. By creating an exclusive reference while a shared reference exists, the iterator breaks the aliasing guarantees, leading to undefined behavior. This flaw occurs because the iterator’s internal pointer is used in a manner that conflicts with Rust’s ownership system, potentially invalidating memory accesses. Although the issue is subtle and requires specific conditions to trigger, it undermines Rust’s safety promises, as safe code could inadvertently cause memory corruption. The problem stems from unsafe code within the iterator that improperly manages borrows, allowing simultaneous mutable and shared accesses. This can result in data races or memory inconsistencies in concurrent environments, though the severity is low due to the narrow scope of impact. Fixing this requires restructuring the iterator to avoid creating conflicting references, possibly by using raw pointers or adjusting the borrowing hierarchy. Developers using this crate might experience crashes or unpredictable behavior in their applications, highlighting the importance of rigorous unsafe code audits. The vulnerability underscores the challenges in maintaining soundness when interfacing safe and unsafe Rust code, necessitating careful validation of borrowing patterns.
Platform: Rust crate
Version: Affected versions
Vulnerability: Stacked Borrows violation
Severity: Low
date: Jan 7 2026
Prediction: Patch expected soon
What Undercode Say:
Bash commands:
`cargo audit`
`cargo update crate`
`checksec –file`
Codes:
let mut iter = map.iter_mut(); iter.next();
unsafe { ptr::read() }
[repr(C)] struct Node;
How Exploit:
Trigger undefined behavior via safe Rust code calling `IterMut` methods repeatedly, potentially causing memory corruption or crashes in concurrent scenarios.
Protection from this CVE
Update crate version, avoid `IterMut` usage, use alternative iterators, audit unsafe code.
Impact:
Low severity, memory safety compromised, possible crashes, hard-to-exploit.
🎯Let’s Practice Exploiting & Learn Patching For Free:
Sources:
Reported By: github.com
Extra Source Hub:
Undercode
