virtualenv CVE-2026-113724

Requires a local user on a POSIX system who can plant a symlink inside a read-only directory that virtualenv's safe_delete() will traverse; the deletion of that entry must fail so the onerror handler runs and calls os.chmod() on the symlink target, following the link. The symlink target must be owned by the invoking (victim) user and mode-changeable by them, and must start out not writable. For a different account to actually abuse the widened mode, that account must be able to traverse the target's parent directories. Limiting factors: local access only, a specific read-only-directory/symlink filesystem layout, a genuine deletion failure to trigger the handler, the victim actually running virtualenv, and the fact that root does not reach the demonstrated failure path - all of which sharply narrow realistic exploitation.

Signals converge on LOW real-world priority despite the symlink-following (CWE-59) root cause. The provided CVSS 3.1 vector (AV:L/AC:H/PR:L/UI:N) describes a local, high-complexity, authenticated-only issue with only partial (Low) impact, yielding a base score of 4.5 (Medium-low). No EPSS score, KEV listing, or public POC is present in the supplied intelligence, so exploitation status is 'no public exploit identified at time of analysis' and there is no SSVC decision data to weigh. The attack requires an unusual filesystem setup (a planted symlink inside a read-only directory, a deletion that fails and triggers the retry handler, and a target owned by and mode-changeable by the invoking user), and the advisory itself notes root does not reach the failure path and the operation never reads the target - all of which strongly bound exploitability. Conflicting signal to flag: the CVSS vector and the 'Information Disclosure' tag imply confidentiality impact, but the description explicitly states the operation does not read the target and only widens write permissions, so the labeled impact is integrity/permission tampering, not disclosure - verify impact classification against the vendor advisory. Net: a legitimate hardening fix, not an urgent, widely-exploitable threat.

On a shared POSIX host, a local user plants a symlink inside a read-only directory that virtualenv will attempt to clean up; when safe_delete() fails to remove the entry, its onerror handler calls os.chmod() on the symlink's target (following the link) and adds owner-write, leaving a file the invoking user owns but did not intend to expose in a writable state. A co-resident account that can traverse the target's parent directories then tampers with that file. No public exploit code is identified, and the high attack complexity (AC:H) plus required local, low-privilege access make opportunistic exploitation unlikely.