jackson-dataformats-binary: CBOR parser does not enforce StreamReadConstraints.maxNameLength, enabling memory-exhaustion denial of service

The CBOR parser in FasterXML jackson-dataformats-binary never invokes StreamReadConstraints.validateNameLength() when decoding JSON object property names, so the maxNameLength limit is not enforced for this format. CBORParser._decodeLongerName() decodes a definite-length property name with no length check, and CBORParser._decodeChunkedName() delegates to the value-oriented _finishChunkedText() routine, which validates maxStringLength rather than maxNameLength. An attacker who can have a CBOR document parsed may therefore embed a single property name of unbounded length; the parser buffers the whole name in memory before returning it, whatever maxNameLength is configured to. Because StreamReadConstraints.maxDocumentLength is also disabled by default, nothing else bounds the name under default settings, so the only limits are the attacker's upload capacity and available heap, leading to memory exhaustion and denial of service. No privileges beyond the ability to submit data to a parsing endpoint are required, and exploitation needs only that the bytes reach CBORFactory parsing, directly or through an ObjectMapper configured with the CBOR module. jackson-core's own JSON parsers enforce maxNameLength incrementally during name decoding; this gap is specific to the binary formats. maxNameLength and validateNameLength were introduced in jackson-core 2.16.0, so releases before 2.16.0 do not contain the constraint that is left unenforced. This issue is tracked together with the Smile parser defect in the same vendor advisory, GHSA-3v8f-v6vx-fmrm, which covers both binary formats. The CBOR parser defect (jackson-dataformats-binary issue #725) is CVE-2026-68495; the Smile parser defect (issue #726) is assigned CVE-2026-68496.

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