Groovy Libraries Plugin CVE-2026-48921

Exploitation requires that the attacker can control the content of a shared library that is actually used by a Pipeline job - concretely, write/commit access to the SCM repository backing a global, folder, or automatically-loaded shared library, or the ability to define such a library, plus an authenticated Jenkins account (CVSS PR:L). The malicious symlink must be present in a library that a job loads and checks out on the controller. Limiting factors: this is NOT remote-unauthenticated against a default install - it needs an authenticated, low-privileged actor with library-content control, the targeted job must consume the attacker-influenced library, and CVSS AC:H signals additional non-trivial conditions (a usable symlink target path on the controller and a build that surfaces the read content). It is constrained to environments where library authors are less trusted than the controller's filesystem, such as multi-tenant or shared Jenkins instances.

Signals are mixed and should be weighed deliberately. The CVSS base score is 7.5 with vector AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H - network reachable, but with High attack complexity and requiring Low (i.e., authenticated) privileges. Notably, the CVSS impact metrics (C:H/I:H/A:H) overstate the effect described: the description and the 'Information Disclosure' tag indicate arbitrary file READ only, which would normally map to C:H/I:N/A:N - verify the integrity/availability impact with the vendor, as it may be a conservative Jenkins scoring convention rather than a true write/DoS primitive. SSVC reinforces a lower urgency: Exploitation=none, Automatable=no, Technical Impact=total. No KEV listing and no public exploit exist. The practical gate is that the attacker must already be able to control library content used by a job, which limits this to insiders or users with write access to a library repo; combined with AC:H this is meaningful but not wormable. Realistic priority: moderate - patch in the normal cycle, prioritized higher in multi-tenant Jenkins where library authors are less trusted than controller secrets.

A developer with write access to a Git repository used as a Jenkins shared library commits a symbolic link pointing at a sensitive path on the controller (for example, a credentials or secrets file). When a Pipeline job loads that library, the plugin follows the symlink and the linked file's contents become readable to the build, which then prints or copies the data out. No public proof-of-concept is identified, and the High attack complexity reflects the need to control library content and have a job consume it.