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.
CVE-2026-91777
This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5%, top 59% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- High severity, but no confirmed exploitation yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 7.5
- EG Score
- 7.5(medium)
- EG Risk
- 65(Attend)EG Risk 65/100SSVC: Attend
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity75% × 45%Exploitation40% × 40%Automatability100% × 15%Action: Remediate soon — notable exploitation risk. - EPSS PROB
- 0%
- EPSS %ILE
- 41%
- KEV
- Not listed
Published
September 23, 2026
Last Modified
September 23, 2026
Advisory Details (2)
Auto-updated Sep 23, 2026Avoid quadratic forward-reference resolution in Collection/Map deserializers [CVE-2026-91777] by pjfanning · Pull Request #6204 · FasterXML/jackson-databind · GitHub
https://github.com/FasterXML/jackson-databind/issues/6204jackson-databind quadratic forward-reference completion · Advisory · FasterXML/jackson-databind · GitHub
https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-cxp5-3px4-pw24Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 7× in last 7d / 7× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-09-24 02:16 UTCEG score recompute
- 2026-09-23 17:54 UTCEPSS rescore
- 2026-09-23 15:20 UTCEG score recompute
- 2026-09-23 14:24 UTCEG score recompute
- 2026-09-23 03:27 UTCEG score recompute
- 2026-09-23 02:28 UTCEG score recompute
- 2026-09-23 02:27 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2026-91777?
When was CVE-2026-91777 disclosed?
Is CVE-2026-91777 actively exploited?
What is the CVSS score of CVE-2026-91777?
How do I remediate CVE-2026-91777?
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-91777
Is Your Infrastructure Affected by CVE-2026-91777?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.