CVE-2026-68496

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

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Published Oct 1, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
Description
The Smile 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. SmileParser._handleLongFieldName() grows its internal name buffer through an unconstrained _growArrayTo() call and performs no length validation. An attacker who can have a Smile 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 SmileFactory parsing, directly or through an ObjectMapper configured with the Smile 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 CBOR parser defect in the same vendor advisory, GHSA-3v8f-v6vx-fmrm, which covers both binary formats. The Smile parser defect (jackson-dataformats-binary issue #726) is CVE-2026-68496; the CBOR parser defect (issue #725) is assigned CVE-2026-68495.

Remediation

Vendor Solution

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 The 2.16.x, 2.17.x, 2.19.x, 2.20.x and 3.0.x lines received no fix on their own branch and are no longer maintained upstream.

Vendor 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 SmileFactory, and cap JVM heap so a single document cannot exhaust process memory. Avoid parsing untrusted Smile input where these limits cannot be applied.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Fasterxml
Fasterxml jackson-dataformats-binary
Vendors & Products Fasterxml
Fasterxml jackson-dataformats-binary
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}
Type Values Removed Values Added
Description The Smile 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. SmileParser._handleLongFieldName() grows its internal name buffer through an unconstrained _growArrayTo() call and performs no length validation. An attacker who can have a Smile 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 SmileFactory parsing, directly or through an ObjectMapper configured with the Smile 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 CBOR parser defect in the same vendor advisory, GHSA-3v8f-v6vx-fmrm, which covers both binary formats. The Smile parser defect (jackson-dataformats-binary issue #726) is CVE-2026-68496; the CBOR parser defect (issue #725) is assigned CVE-2026-68495.
Title jackson-dataformats-binary: Smile parser does not enforce StreamReadConstraints.maxNameLength, enabling memory-exhaustion denial of service
Weaknesses CWE-400
CWE-770
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}
Weaknesses

Sources

Status
PUBLISHED
Assigner
HeroDevs
Published
Updated
Oct 1, 2026, 6:15 PM
Reserved
Jul 30, 2026, 3:20 PM

View source JSON

Updated
Oct 1, 2026, 6:15 PM

JSON

Status
Awaiting Analysis
Published
Oct 1, 2026, 6:17 PM
Modified
Oct 2, 2026, 6:44 PM

View source JSON

No data.

Updated
Oct 1, 2026, 7:15 PM

JSON