PEAR Archive_Tar Improper Link Resolution
CVE-2020-36193 is a high-severity improper limitation of a pathname to a restricted directory vulnerability in Archive Tar from PHP, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Archive Tar versions: 1.4.11 and earlier. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on August 25, 2022, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Update Drupal to 7.78 or 8.9.13 or 9.0.11 or 9.1.3, whichever matches your release line, or a later version.
- CISA's required action: Apply updates per vendor instructions.
- 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 |
|---|---|---|---|
| PHP | Archive Tar | 1.4.11 and earlier | Not stated |
| Fedora Project | Fedora | 32; 33; 34; 35 | Not stated |
| Debian | Debian Linux | 9.0; 10.0 | Not stated |
| Drupal | Drupal | 7.0 up to, but not including, 7.78; 8.9.0 up to, but not including, 8.9.13; 9.0.0 up to, but not including, 9.0.11; 9.1.0 up to, but not including, 9.1.3 | 7.78, 8.9.13, 9.0.11, 9.1.3 |
Version data comes from NVD's product matching. 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
- NoneNo data is disclosed.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.5 | High | NVD |
| CVSS 3.1 | 7.5 | High | CISA (ADP) |
| CVSS 2.0 | 5.0 | Medium | NVD |
Official description
Tar.php in Archive_Tar through 1.4.11 allows write operations with Directory Traversal due to inadequate checking of symbolic links, a related issue to CVE-2020-28948.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Limitation of a Pathname to a Restricted Directory
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.
How developers prevent this class of flaw
- For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
- Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth.
More Improper Limitation of a Pathname to a Restricted Directory vulnerabilities (CWE-22)
Timeline
- CVE record published.
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- Deadline for US federal agencies to remediate, set by CISA.
- CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Third-party and government advisories
- lists.debian.org/debian-lts-announce/2021/01/msg00018.htmlMailing List, Third Party Advisory
- lists.debian.org/debian-lts-announce/2021/04/msg00007.htmlMailing List, Third Party Advisory
- security.gentoo.org/glsa/202101-23Third Party Advisory
- debian.org/security/2021/dsa-4894Third Party Advisory
- drupal.org/sa-core-2021-001Third Party Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-36193US Government Resource
Other vulnerabilities in Archive Tar
- 7.8 High severity
Recent Improper Limitation of a Pathname to a Restricted Directory vulnerabilities
- 7.8 High severity
- 7.5 High severity
- 6.5 Medium severity
- 9.8 Critical severity
- 7.5 High severity
- 4.3 Medium severity
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