curl: Allocation of Resources Without Limits or Throttling
CVE-2023-38039 is a high-severity allocation of resources without limits or throttling vulnerability in curl, 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. The record lists version 8.3.0 as the first without the flaw, so updating curl to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 56.2% chance of exploitation within 30 days, which is in the top 0.94% of all scored CVEs.
Exploitation in the next 30 days is more likely than not, according to EPSS.
What to do
- Update curl to 8.3.0 or a later version.
- Update Windows 10 1809 to 10.0.17763.5122 or a later version.
- Update Windows 10 21h2 to 10.0.19044.3693 or a later version.
- 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 |
|---|---|---|---|
| Curl | curl | 8.3.0 up to, but not including, 8.3.0 | 8.3.0 |
| Fedora Project | Fedora | 37; 38; 39 | Not stated |
| Microsoft | Windows 10 1809 | before 10.0.17763.5122 | 10.0.17763.5122 |
| Microsoft | Windows 10 21h2 | before 10.0.19044.3693 | 10.0.19044.3693 |
| Microsoft | Windows 10 22h2 | before 10.0.19045.3693 | 10.0.19045.3693 |
| Microsoft | Windows 11 21h2 | before 10.0.22000.2600 | 10.0.22000.2600 |
| Microsoft | Windows 11 22h2 | before 10.0.22621.2715 | 10.0.22621.2715 |
| Microsoft | Windows 11 23h2 | before 10.0.22631.2715 | 10.0.22631.2715 |
| Microsoft | Windows Server 2019 | before 10.0.17763.5122 | 10.0.17763.5122 |
| Microsoft | Windows Server 2022 | before 10.0.20348.2113 | 10.0.20348.2113 |
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
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.5 | High | NVD |
| CVSS 3.1 | 7.5 | High | CISA (ADP) |
Official description
When curl retrieves an HTTP response, it stores the incoming headers so that they can be accessed later via the libcurl headers API. However, curl did not have a limit in how many or how large headers it would accept in a response, allowing a malicious server to stream an endless series of headers and eventually cause curl to run out of heap memory.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Allocation of Resources Without Limits or Throttling
The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
How developers prevent this class of flaw
- Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.
- Limit the amount of resources that are accessible to unprivileged users. Set per-user limits for resources. Allow the system administrator to define these limits. Be careful to avoid CWE-410.
- 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.
More Allocation of Resources Without Limits or Throttling vulnerabilities (CWE-770)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- hackerone.com/reports/2072338Exploit, Issue Tracking, Third Party Advisory
Third-party and government advisories
- seclists.org/fulldisclosure/2023/Oct/17Mailing List, Third Party Advisory
- seclists.org/fulldisclosure/2024/Jan/34Mailing List, Third Party Advisory
- seclists.org/fulldisclosure/2024/Jan/37Mailing List, Third Party Advisory
- seclists.org/fulldisclosure/2024/Jan/38Mailing List, Third Party Advisory
- security.gentoo.org/glsa/202310-12Third Party Advisory
- security.netapp.com/advisory/ntap-20231013-0005/Third Party Advisory
- support.apple.com/kb/HT214036Third Party Advisory
- support.apple.com/kb/HT214057Third Party Advisory
- support.apple.com/kb/HT214058Third Party Advisory
- support.apple.com/kb/HT214063Third Party Advisory
- insyde.com/security-pledge/SA-2023064Third Party Advisory
Other references
Other vulnerabilities in curl
- 7.5 High severity
- 9.1 Critical severity
- 7.5 High severity
- 7.5 High severity
- 8.1 High severity
- 9.1 Critical severity
Recent Allocation of Resources Without Limits or Throttling vulnerabilities
- 9.8 Critical severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
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