Tink: Improper Encoding or Escaping of Output
CVE-2024-4420 is a high-severity improper encoding or escaping of output vulnerability in Tink from Google, 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 2.1.3 as the first without the flaw, so updating Tink to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.23% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Tink to 2.1.3 or a later version.
- Update Tink C++ to 2.1.3 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 |
|---|---|---|---|
| Tink | 2.0.0 up to, but not including, 2.1.3 | 2.1.3 | |
| Tink (Legacy) | 1.7.0 and earlier | Not stated | |
| Tink C++ | before 2.1.3 | 2.1.3 |
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 4.0 | 6.8 | Medium | CNA (google.com) |
| CVSS 3.1 | 7.5 | High | NVD |
Official description
There exists a Denial of service vulnerability in Tink-cc in versions prior to 2.1.3. * An adversary can crash binaries using the crypto::tink::JsonKeysetReader in tink-cc by providing an input that is not an encoded JSON object, but still a valid encoded JSON element, for example a number or an array. This will crash as Tink just assumes any valid JSON input will contain an object. * An adversary can crash binaries using the crypto::tink::JsonKeysetReader in tink-cc by providing an input containing many nested JSON objects. This may result in a stack overflow. We recommend upgrading to version 2.1.3 or above
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Encoding or Escaping of Output
The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved.
How developers prevent this class of flaw
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using the ESAPI Encoding control or a similar tool, library, or framework. These will help the programmer encode outputs in a manner less prone to error. Alternately, use built-in functions, but consider using wrappers in case those functions are discovered to have a vulnerability.
- If available, use structured mechanisms that automatically enforce the separation between data and code. These mechanisms may be able to provide the relevant quoting, encoding, and validation automatically, instead of relying on the developer to provide this capability at every point where output is generated. For example, stored procedures can enforce database query structure and reduce the likelihood of SQL injection.
- Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages. Study all expected communication protocols and data representations to determine the required encoding strategies.
More Improper Encoding or Escaping of Output vulnerabilities (CWE-116)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- github.com/tink-crypto/tink-cc/issues/4Issue Tracking, Third Party Advisory
Recent Improper Encoding or Escaping of Output vulnerabilities
- 9.4 Critical severity
- 9.8 Critical severity
- 7.5 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 8.2 High severity
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