netty: Null Byte Interaction Error (Poison Null Byte)
CVE-2026-62380 is a high-severity null byte interaction error (poison null byte) vulnerability in netty, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 4.2.16.Final, 4.1.137.Final as the first without the flaw, so updating netty to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.25% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update netty to 4.2.16.Final or 4.1.137.Final, whichever matches your release line, or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Netty | netty | 4.2.0.Final up to, but not including, 4.2.16.Final; before 4.1.137.Final | 4.2.16.Final, 4.1.137.Final |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 6.3 | Medium | CNA (vulncheck.com) |
| CVSS 3.1 | 7.5 | High | NVD |
Official description
Netty (io.netty:netty-codec-socks) versions 4.2.0.Final through 4.2.16.Final and 4.1.x through 4.1.136.Final contain null byte, CRLF, and credential injection vulnerabilities in the SOCKS4 (Socks4ClientEncoder) and SOCKS5 (Socks5ClientEncoder) client encoders, which fail to validate domain address and authentication (username/password) fields. An attacker able to control these fields can inject null bytes or CRLF characters to truncate or alter values, potentially enabling domain spoofing, SOCKS4 userid truncation, authentication data injection, and protocol confusion. Fixed in 4.2.17.Final and 4.1.137.Final.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Null Byte Interaction Error (Poison Null Byte)
The product does not properly handle null bytes or NUL characters when passing data between different representations or components.
How developers prevent this class of flaw
- Remove null bytes from all incoming strings.
More Null Byte Interaction Error (Poison Null Byte) vulnerabilities (CWE-626)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- vulncheck.com/advisories/netty-before-final-socks-proxy-null-byte-injectionThird Party Advisory
Other vulnerabilities in netty
- 7.3 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
Spotted an error? Tell us.