CVE-2026-68496 Denial of service in jackson-dataformats-binary
Attackers can cause memory exhaustion and denial of service by submitting Smile documents with unbounded property names, bypassing length constraints in the Jackson binary data parser.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-68496?
CVE-2026-68496 is a high-severity denial of service vulnerability in FasterXML jackson-dataformats-binary, published on 1 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-68496?
How do I fix CVE-2026-68496?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-68496 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-68496 exists.
Sources
Also known as CLEANSTART-2026-CH00220, CLEANSTART-2026-XU96478, DEBIAN-CVE-2026-68496, GHSA-fvrx-r5jq-295q, UBUNTU-CVE-2026-68496.