What’s Vulnerable › Vulnerabilities

CVE-2026-61695: Wire Swift runtime: negative LENGTH_DELIMITED length in skipGroup() crashes any protobuf-decoding service

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-23 · updated 2026-09-30
• Weakness: CWE-129

Description

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.

Affected products

• square wire: before 6.4.1; from 7.0.0-alpha01, < 7.0.0-alpha04

References

• https://github.com/square/wire/commit/24043b6b3a5e5974a978f2745b76d50b31407c1c
• https://github.com/square/wire/commit/81ff7f24a6795d9a8be2e03f272b2d979a5d2c7e
• https://github.com/square/wire/pull/3616
• https://github.com/square/wire/releases/tag/6.4.1
• https://github.com/square/wire/releases/tag/7.0.0-alpha04
• https://github.com/square/wire/security/advisories/GHSA-86wm-r4c5-2rc9
• https://github.com/square/wire/security/advisories/GHSA-86wm-r4c5-2rc9

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