---
title: "CVE-2026-91777: FasterXML jackson-databind - Denial of Service"
description: "FasterXML jackson-databind contains a performance issue caused by linear scanning of pending-reference accumulator in identity-enabled collections or maps, letting attackers cause quadratic CPU usage during deserialization, exploit requires deserialization of attacker-controlled JSON."
url: https://panop.io/threat-heartbeat/CVE-2026-91777/
---

# CVE-2026-91777 FasterXML jackson-databind - Denial of Service

FasterXML jackson-databind contains a performance issue caused by linear scanning of pending-reference accumulator in identity-enabled collections or maps, letting attackers cause quadratic CPU usage during deserialization, exploit requires deserialization of attacker-controlled JSON.

CVSS base score 7.5 /10

High

CISA KEV

Not listed

Public exploit

None known

EPSS

0.45% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-91777)

## Details

Type

Denial of Service

Impact

Denial Of Service

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Published

23 September 2026

Updated

15 October 2026

Weakness

[CWE-400](https://cwe.mitre.org/data/definitions/400.html)

## Vendor fix

Update to the latest version with the fix replacing linear lookup with keyed pending-reference structure.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-91777](https://nvd.nist.gov/vuln/detail/CVE-2026-91777)
- [https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-cxp5-3px4-pw24](https://github.com/FasterXML/jackson-databind/security/advisories/GHSA-cxp5-3px4-pw24)
- [https://github.com/FasterXML/jackson-databind/issues/6204](https://github.com/FasterXML/jackson-databind/issues/6204)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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