CVE-2026-89407

What it is

NumberInput.looksLikeValidNumber() in FasterXML jackson-core pre-validates "stringified numbers" with two regular expressions: PATTERN_FLOAT ([+-]?[0-9]*[\.]?[0-9]+([eE][+-]?[0-9]+)?), present since 2.17.0, and PATTERN_FLOAT_TRAILING_DOT, added in 2.17.2. PATTERN_FLOAT places adjacent quantifiers over the same character class -- an optional [0-9]* run, an optional dot, then a required [0-9]+ run -- so input that ultimately fails to match forces Java's backtracking engine to retry every possible split point of the digit run.  Matching cost therefore grows with the square of the input length.  An attacker who can supply JSON that an application deserializes into a numeric target type reaches this method through jackson-databind's default String-to-number coercion (StdDeserializer and NumberDeserializers for BigDecimal, BigInteger, Double and Float).  Because StreamReadConstraints.maxStringLength defaults to 20,000,000 characters, no constraint bounds the input before it reaches the regex.  Testing by the reporter confirmed O(n^2) growth across five consecutive input-size doublings, with a single 160,000-character string consuming roughly 74 seconds in one call; a small number of concurrent requests of ordinary body size can therefore exhaust a server's request-handling thread pool.  The affected method does not exist before 2.17.0, so 2.16.x and earlier releases are not affected.  The fix replaces both regular expressions with a hand-rolled single-pass scan.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of service disruption.

Exploit odds

0.6% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-09-11 16:07 UTC ReservedThe CVE id was reserved by its CNA
2. 2026-09-22 15:17 UTC PublishedDisclosed publicly on CVE.org and NVD
3. 2026-09-22 20:00 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.6% in the next 30 days (EPSS).
• Severity: 7.5 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-09-22 15:17 UTC

Last modified

2026-09-22 20:00 UTC

Exploit probability

0.6% · EPSS, next 30 days

Weakness

CWE-400 · Uncontrolled resource consumption

Record status

Deferred

Attack profile CVSS 3.1 · 7.5

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-89407.md and follow it. Check whether this project is affected by CVE-2026-89407. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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