CVE-2021-41272 SHL, SHR, and SAR operations trigger native exception at key values in besu
A signed type coercion error in Besu causes native exceptions during specific shift operations, leading to network forks or validator failures.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2021-41272?
CVE-2021-41272 is a high-severity denial of service vulnerability in hyperledger besu, published on 13 Dec 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Besu is an Ethereum client written in Java. Starting in version 21.10.0, changes in the implementation of the SHL, SHR, and SAR operations resulted in the introduction of a signed type coercion error in values that represent negative values for 32 bit signed integers. Smart contracts that ask for shifts between approximately 2 billion and 4 billion bits (nonsensical but valid values for the operation) will fail to execute and hence fail to validate. In networks where vulnerable versions are mining with other clients or non-vulnerable versions this will result in a fork and the relevant transactions will not be included in the fork. In networks where vulnerable versions are not mining (such as Rinkeby) no fork will result and the validator nodes will stop accepting blocks. In networks where only vulnerable versions are mining the relevant transaction will not be included in any blocks. When the network adds a non-vulnerable version the network will act as in the first case. Besu 21.10.2 contains a patch for this issue. Besu 21.7.4 is not vulnerable and clients can roll back to that version. There is a workaround available: Once a transaction with the relevant shift operations is included in the canonical chain, the only remediation is to make sure all nodes are on non-vulnerable versions.
Weakness: CWE-681
Which versions are affected by CVE-2021-41272?
It affects 1 product.
Products include Linuxfoundation Besu.
How do I fix CVE-2021-41272?
No fix has been published for CVE-2021-41272 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2021-41272 being exploited?
There is no known exploitation of CVE-2021-41272 in the wild and no public exploit code.
Other vulnerabilities in hyperledger besu
Sources
Also known as GHSA-7pg2-p5vj-xp5h.