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CVE-2026-89407— jackson-core: quadratic backtracking in NumberInput.PATTERN_FLOAT via looksLikeValidNumber() enables ReDoS

Quick assessment

Affected
FasterXML jackson-core
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

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. PATTE

CVSS 7.5 · High

Affected Version Matrix 5

VendorProduct Version RangeStatus
FasterXML jackson-core 2.17.0≤ 2.18.10 affected
2.19.0≤ 2.21.6 affected
2.22.0≤ 2.22.2 affected
3.0.0≤ 3.1.6 affected
3.2.0≤ 3.2.1 affected
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I. Basic Information for CVE-2026-89407

Vulnerability Information

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Vulnerability Title
jackson-core: quadratic backtracking in NumberInput.PATTERN_FLOAT via looksLikeValidNumber() enables ReDoS
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
CWE-1333
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
FasterXML jackson-core 2.17.0 ~ 2.18.10 -
FasterXML jackson-core 3.0.0 ~ 3.1.6 -

II. Public POCs for CVE-2026-89407

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III. Intelligence Information for CVE-2026-89407

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Patches & Fixes for CVE-2026-89407 (2)

Other References for CVE-2026-89407 (2)

IV. Related Vulnerabilities

Same product: jackson-core
Same vendor: FasterXML
Same weakness: CWE-1333

V. Comments for CVE-2026-89407

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