CVE-2026-91777: jackson-databind: quadratic forward-reference completion in Collection and Map deserializers
FasterXML · jackson-databind
No fix listed · Affected: FasterXML jackson-databind · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 42% of scored CVEs
DescriptionCVE.org
Forward-reference completion for @JsonIdentityInfo object IDs in FasterXML jackson-databind performs a linear scan of the pending-reference accumulator for every resolved ID. The affected paths are CollectionDeserializer.CollectionReferringAccumulator.resolveForwardReference() and the equivalent implementation in MapDeserializer. When a document first creates N unresolved object-ID references in an identity-enabled collection or map and then defines those same IDs in reverse order, completion performs on the order of N * (N + 1) / 2 identity comparisons, so a shallow document whose size grows linearly causes quadratic CPU work during deserialization. The reporter instrumented equals() calls on the ID class and measured exactly 2,003,000 comparisons at N = 2,000, against zero comparisons in the pending-reference lookup path for an equally sized control in which every reference was already resolved. The input requires no deep nesting and no syntactically unusual JSON. Exploitation requires an application that deserializes attacker-influenced JSON into an identity-enabled collection or map. The fix replaces the repeated linear lookup with a keyed pending-reference structure.
Affected products2
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- FasterXML · jackson-databindfrom 2.5.0 up to and including 2.18.10; from 2.19.0 up to and including 2.21.6; from 2.22.0 up to and including 2.22.2
- FasterXML · jackson-databindfrom 3.0.0 up to and including 3.1.6; from 3.2.0 up to and including 3.2.2
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Unlikely (under 1%). EPSS under 1%, or no score yet.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Vendor
- FasterXML
- Published
- September 2026
CoverageNo articles yet
No CyberSIXT article names CVE-2026-91777 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.