Square Wire up to 6.4.0/7.0.0-alpha03 Swift Runtime ProtoReader.skipGroup buffer overflow

Summaryinfo

A vulnerability marked as problematic has been reported in Square Wire up to 6.4.0/7.0.0-alpha03. Affected is the function ProtoReader.skipGroup of the component Swift Runtime. The manipulation leads to buffer overflow. This vulnerability is listed as CVE-2026-61695. The attack may be initiated remotely. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Square Wire up to 6.4.0/7.0.0-alpha03. This issue affects the function ProtoReader.skipGroup of the component Swift Runtime. The manipulation with an unknown input leads to a buffer overflow vulnerability. Using CWE to declare the problem leads to CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. Impacted is availability. The summary by CVE is:

Wire provides gRPC and protocol buffers for Android, Kotlin, Swift, and Java. Prior to 6.4.1 and 7.0.0-alpha04, Wire's Swift runtime ProtoReader.skipGroup(expectedEndTag:unknownFieldsWriter:) accepts a negative length for a LENGTH_DELIMITED field inside an unknown START_GROUP field. ProtoReader.readData() forwards the negative count to ReadBuffer.readData(count:), whose upper-bound-only check permits the value to reach Foundation Data(bytes:count:) and trigger an unrecoverable process trap instead of a catchable ProtoDecoder.Error. Any Swift process decoding untrusted protobuf bytes can be crashed without authentication, user interaction, or knowledge of the target schema. This issue is fixed in versions 6.4.1 and 7.0.0-alpha04.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-61695 since 07/10/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available.

Upgrading to version 6.4.1 or 7.0.0-alpha04 eliminates this vulnerability.

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Productinfo

Vendor

• Square

Name

• Wire

Version

• 6.0
• 6.1
• 6.2
• 6.3
• 6.4.0
• 7.0.0-alpha03

Website

• Product: https://github.com/square/wire/

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