CVE-2026-53783
Description
A time-of-check to time-of-use (TOCTOU) race condition flaw in the rrsync restricted shell wrapper allows authenticated remote attackers to escape directory restrictions. By replacing a validated path component with a symbolic link prior to file transfer execution, an attacker can bypass intended boundary controls and read or write arbitrary files outside the designated directory.
Statement
An Important TOCTOU race condition in rsync's rrsync wrapper allows authenticated users to manipulate symlinks and escape directory boundaries, granting unauthorized read and write access to files outside the intended subtree.
Mitigation
Do not use the rrsync SSH forced-command wrapper until patched packages are applied. If restricted rsync over SSH is strictly required, grant access only to SSH identities that are fully trusted with the host account's entire filesystem privileges, as rrsync cannot safely enforce directory boundaries. Note that standard rsync daemon firewall controls (TCP 873) do not mitigate this flaw, as execution occurs entirely over SSH (TCP 22).
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.1 | N/A | 8.1 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Understanding the Weakness (CWE)
Confidentiality,Integrity,Access Control
Technical Impact: Read Files or Directories; Modify Files or Directories; Bypass Protection Mechanism
An attacker may be able to traverse the file system to unintended locations and read or overwrite the contents of unexpected files. If the files are used for a security mechanism then an attacker may be able to bypass the mechanism.
Other
Technical Impact: Execute Unauthorized Code or Commands
Windows simple shortcuts, sometimes referred to as soft links, can be exploited remotely since a ".LNK" file can be uploaded like a normal file. This can enable remote execution.
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