Adobe Acrobat and Reader Double Free
CVE-2018-4990 is a high-severity double free vulnerability in Adobe Acrobat and Reader 2018.011.20038 and earlier, 2017.011.30079 and earlier, and 2015.006.30417 and earlier versions, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. CISA added it to the Known Exploited Vulnerabilities catalogue on June 8, 2022, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Check which version of Adobe Acrobat and Reader 2018.011.20038 and earlier, 2017.011.30079 and earlier, and 2015.006.30417 and earlier versions you run against the affected versions below, and install the vendor's latest release.
- CISA's required action: Apply updates per vendor instructions.
- Read the advisory on helpx.adobe.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.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Adobe Acrobat and Reader 2018.011.20038 and earlier, 2017.011.30079 and earlier, and 2015.006.30417 and earlier versions | Adobe Acrobat and Reader 2018.011.20038 and earlier, 2017.011.30079 and earlier, and 2015.006.30417 and earlier versions | Not specified in the record | Not stated |
| Adobe | Acrobat Dc | 15.006.30060 through 15.006.30417; 15.008.20082 through 18.011.20038; 17.011.30059 through 17.011.30079 | Not stated |
| Adobe | Acrobat Reader Dc | 15.006.30060 through 15.006.30417; 15.008.20082 through 18.011.20038; 17.011.30059 through 17.011.30079 | 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
- RequiredA user must take an action such as opening a file or link.
- 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:R/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.8 | High | NVD |
| CVSS 3.1 | 8.8 | High | CISA (ADP) |
| CVSS 2.0 | 6.8 | Medium | NVD |
Official description
Adobe Acrobat and Reader versions 2018.011.20038 and earlier, 2017.011.30079 and earlier, and 2015.006.30417 and earlier have a Double Free vulnerability. Successful exploitation could lead to arbitrary code execution in the context of the current user.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Double Free
The product calls free() twice on the same memory address.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly. If the language is object oriented, ensure that object destructors delete each chunk of memory only once.
- Use a static analysis tool to find double free instances.
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: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-4990Third Party Advisory, US Government Resource
Recent Double Free vulnerabilities
- 8.8 High severity
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