php-svg-lib: External Control of System or Configuration Setting
CVE-2023-50252 is a critical-severity external control of system or configuration setting vulnerability in php-svg-lib from Dompdf, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected php-svg-lib versions: < 0.5.1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 24.8% chance of exploitation within 30 days, which is in the top 2.07% of all scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of php-svg-lib you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Dompdf | php-svg-lib | < 0.5.1 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.3 | High | CNA (github.com) |
| CVSS 3.1 | 9.8 | Critical | NVD |
Official description
php-svg-lib is an SVG file parsing / rendering library. Prior to version 0.5.1, when handling `<use>` tag that references an `<image>` tag, it merges the attributes from the `<use>` tag to the `<image>` tag. The problem pops up especially when the `href` attribute from the `<use>` tag has not been sanitized. This can lead to an unsafe file read that can cause PHAR Deserialization vulnerability in PHP prior to version 8. Version 0.5.1 contains a patch for this issue.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: External Control of System or Configuration Setting
One or more system settings or configuration elements can be externally controlled by a user.
How developers prevent this class of flaw
- Compartmentalize the system to have safe areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
- Because setting manipulation covers a diverse set of functions, any attempt at illustrating it will inevitably be incomplete. Rather than searching for a tight-knit relationship between the functions addressed in the setting manipulation category, take a step back and consider the sorts of system values that an attacker should not be allowed to control.
- In general, do not allow user-provided or otherwise untrusted data to control sensitive values. The leverage that an attacker gains by controlling these values is not always immediately obvious, but do not underestimate the creativity of the attacker.
More External Control of System or Configuration Setting vulnerabilities (CWE-15)
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Advisories
- github.com/dompdf/php-svg-lib/security/advisories/GHSA-jq98-9543-m4crExploit, Mitigation
Patches and release notes
Other vulnerabilities in php-svg-lib
- 9.8 Critical severity
- 7.5 High severity
Recent External Control of System or Configuration Setting vulnerabilities
- 8.8 High severity
- 8.8 High severity
- 8.8 High severity
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