CVE-2026-27727 swaldman CVE debrief

Who should care

Developers and administrators using the mchange-commons-java library in their applications should be aware of this vulnerability. The vulnerability can be exploited remotely, and an attacker can execute malicious code on the affected system. Users of c3p0, a library that uses mchange-commons-java, are also affected. Additionally, Red Hat users who have applied errata RHSA-2026:14873, RHSA-2026:14874, RHSA-2026:18054, or other related errata should review their systems for potential exposure.

Technical summary

The mchange-commons-java library includes an independent implementation of JNDI dereferencing, which can be provoked to download and execute malicious code. The library's JNDI functionality is gated by configuration parameters that default to restrictive values starting in version 0.4.0. However, versions prior to 0.4.0 should be avoided on application CLASSPATHs. The vulnerability can be mitigated by using version 0.4.0 or later of the library. The CVSS vector for this vulnerability is CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X.

Defensive priority

This vulnerability has a high CVSS score of 8.9 and can be exploited remotely, making it a high-priority issue for defenders to address. Users of affected versions should upgrade to version 0.4.0 or later as soon as possible.

Recommended defensive actions

• Upgrade to version 0.4.0 or later of the mchange-commons-java library.
• Review application CLASSPATHs to ensure that only secure versions of the library are used.
• Implement additional security measures, such as validating and sanitizing input data, to prevent exploitation.
• Monitor systems for potential exposure and apply errata as needed.
• Consider implementing compensating controls, such as network segmentation or access controls, to limit the impact of a potential exploit.

Evidence notes

The CVE-2026-27727 vulnerability was published on February 25, 2026, and last modified on June 30, 2026. The vulnerability has a CVSS score of 8.9 and is considered high-severity. The issue is caused by the mchange-commons-java library's implementation of JNDI functionality, which allows for the download and execution of malicious code. The vulnerability can be exploited remotely, and an attacker can execute malicious code on the affected system.

Official resources