Summary
A vulnerability in Deno's Node.js compatibility runtime allows for cross-session data contamination during simultaneous asynchronous reads from Node.js streams sourced from sockets or files. The issue arises from the re-use of a global buffer (BUF) in stream_wrap.ts used as a performance optimization to limit allocations during these asynchronous read operations. This can lead to data intended for one session being received by another session, potentially resulting in data corruption and unexpected behavior.
Details
A bug in Deno's Node.js compatibility runtime results in data cross-reception during simultaneous asynchronous reads from Node.js network streams. When multiple independent network socket connections are involved, this vulnerability can be triggered. For instance, two separate server sockets that receive data from their respective client sockets and then echo the received data back to the client using Node.js streams may experience an issue where data from one socket may appear on another socket. Due to the improper isolation of the global buffer (BUF), data sent by one socket can end up being incorrectly received by another socket. Consequently, data intended for one session may be exposed to another session, potentially leading to data corruption and unexpected behavior.
This buffer was introduced as a performance optimization to avoid excessive allocations during network read operations.
In cases where the net.Stream is connected to a remote server such as a database or key/value store such as Redis, this may result in a packet received on one connection being presented to another, causing data cross-contamination between multiple users and potentially leaking sensitive information.
It is important to note that this vulnerability does not affect Deno network streams created with the Deno.listen and Deno.connect APIs.
The impact of this issue may extend beyond node.js network streams, however, and may also affect asynchronous reads from non-network node.js Stream such as those created from files.
PoC
Impact
This affects all users of Deno that use the node.js compatibility layer for network communication or other streams, including packages that may require node.js libraries indirectly.
CVE-2024-27935 has a CVSS score of 7.2 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.36.3); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2024-27935? CVE-2024-27935 is a high-severity security vulnerability in deno (rust), affecting versions >= 1.35.1, < 1.36.3. It is fixed in 1.36.3.
- How severe is CVE-2024-27935? CVE-2024-27935 has a CVSS score of 7.2 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of deno are affected by CVE-2024-27935? deno (rust) versions >= 1.35.1, < 1.36.3 is affected.
- Is there a fix for CVE-2024-27935? Yes. CVE-2024-27935 is fixed in 1.36.3. Upgrade to this version or later.
- Is CVE-2024-27935 exploitable, and should I be worried? Whether CVE-2024-27935 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2024-27935 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2024-27935? Upgrade
denoto 1.36.3 or later.