SECURITY.md

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# Security Policy

## Reporting a Vulnerability

Please do not report security vulnerabilities through public GitHub
issues, pull requests or mailing lists.

Report them privately to the Apache Security Team at
security@apache.org, or to the Apache DataSketches PMC at
private@datasketches.apache.org. The Apache Security Team forwards
reports to the PMC and coordinates the process described at
https://www.apache.org/security/.

Please include the affected version, a description of the issue and, if
possible, a way to reproduce it (for example, a serialized sketch that
triggers it).

## Supported Versions

The Apache DataSketches PMC supports only the latest release. Security
fixes are made in the next release and are not backported to earlier
releases. Users should upgrade to the latest release to receive fixes.

## Published Vulnerabilities

Published vulnerabilities and their advisories are listed at
https://datasketches.apache.org/docs/Community/Security.html.

## Security Model

### Deserialization

The deserialization functions of all sketches (the `deserialize()` and
`wrap()` functions that take a byte buffer or a stream) must be safe to
call on arbitrary input, including input crafted by an attacker. A
malformed, truncated or corrupt serialized sketch must be rejected with
an exception, such as `std::invalid_argument`, `std::out_of_range` or
`std::runtime_error`. It must never cause an out-of-bounds read or write,
or other undefined behavior.

A failure to meet this is treated as a security vulnerability.

Applications that deserialize sketches from untrusted sources should
catch these exceptions. Note that a well-formed sketch can legitimately
be large. Applications that accept sketches from untrusted sources
should limit the size of the input they accept.

### Other APIs

Other APIs, such as sketch construction parameters, updates, merges and
queries, assume a caller that follows the documented preconditions. For
example, sketch sizes must be within the documented limits, and a
sketch must not be used concurrently from multiple threads without
external synchronization. Violating a documented precondition is a bug
in the calling application, not a vulnerability in this library.

### Estimates

Sketches produce approximate results with probabilistic error bounds.
An adversary who controls the input data can bias the estimates, for
example by choosing items that hash to specific values when the hash
seed is known. This is inherent to sketching and is not a vulnerability.
Applications where this matters should use a secret, non-default seed.