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CVE-2026-68495

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

High7.5EPSS 0.56%
Published
Updated
Reserved
Assigned by
HeroDevs

Description

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.

Scores

CVSS scores of CVE-2026-68495, by who scored it
Scored byCVSSScoreVector
HeroDevsCNA (assigner)3.1High7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVDNVD · Awaiting Analysis3.1High7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS (exploitation in 30 days)
0.56% · top 53% of all CVEs (6 Nov 2026)
CISA SSVC
Exploitation: poc · Automatable: yes · Technical impact: partial
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The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.

Weakness

Affected products

What to do

Solution: Upgrade to com.fasterxml.jackson.dataformat:jackson-dataformat-cbor 2.18.10, 2.21.6 or 2.22.2, or to tools.jackson.dataformat:jackson-dataformat-cbor 3.1.6 or 3.2.2. The 2.16.x, 2.17.x, 2.19.x, 2.20.x and 3.0.x lines received no fix on their own branch and are no longer maintained upstream.

Workaround: No StreamReadConstraints setting mitigates this: maxNameLength is the control that is not enforced, and maxDocumentLength is disabled by default (-1). Bound request body size ahead of the parser, set StreamReadConstraints.maxDocumentLength explicitly on the CBORFactory, and cap JVM heap so a single document cannot exhaust process memory. Avoid parsing untrusted CBOR input where these limits cannot be applied.

References (4)

Sources

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Record last updated .