jackson-core: quadratic backtracking in NumberInput.PATTERN_FLOAT via looksLikeValidNumber() enables ReDoS
Summary
| CVE | CVE-2026-89407 |
|---|---|
| State | PUBLISHED |
| Assigner | HeroDevs |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-09-22 15:17:21 UTC |
| Updated | 2026-09-22 20:00:03 UTC |
| 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. |
Risk And Classification
Primary CVSS: v3.1 7.5 HIGH from 36c7be3b-2937-45df-85ea-ca7133ea542c
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS: 0.006300000 probability, percentile 0.488360000 (date 2026-09-23)
Problem Types: CWE-400 | CWE-1333 | CWE-1333 CWE-1333 Inefficient Regular Expression Complexity | CWE-400 CWE-400 Uncontrolled Resource Consumption
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | 36c7be3b-2937-45df-85ea-ca7133ea542c | Secondary | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| 3.1 | CNA | CVSS | 7.5 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
CVSS v3.1 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | FasterXML | Jackson-core | affected 2.17.0 2.18.10 maven | Not specified |
| CNA | FasterXML | Jackson-core | affected 2.19.0 2.21.6 maven | Not specified |
| CNA | FasterXML | Jackson-core | affected 2.22.0 2.22.2 maven | Not specified |
| CNA | FasterXML | Jackson-core | affected 3.0.0 3.1.6 maven | Not specified |
| CNA | FasterXML | Jackson-core | affected 3.2.0 3.2.1 maven | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/FasterXML/jackson-core/issues/1649 | 36c7be3b-2937-45df-85ea-ca7133ea542c | github.com | |
| github.com/FasterXML/jackson-core/pull/1650 | 36c7be3b-2937-45df-85ea-ca7133ea542c | github.com | |
| github.com/FasterXML/jackson-core/security/advisories/GHSA-p6pp-m3f8-5c89 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | github.com | |
| github.com/FasterXML/jackson-core/pull/1701 | 36c7be3b-2937-45df-85ea-ca7133ea542c | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: manqingzhou (en)
Additional Advisory Data
Solutions
CNA: Upgrade to com.fasterxml.jackson.core:jackson-core 2.18.11, 2.21.7 or 2.22.3, or to tools.jackson.core:jackson-core 3.1.7 or 3.2.2. The 2.17.x, 2.19.x, 2.20.x and 3.0.x lines received no fix on their own branch and are no longer maintained upstream; consumers of those lines must move forward to a maintained release.
Workarounds
CNA: Until upgrading, lower StreamReadConstraints.maxStringLength well below its default of 20,000,000 characters so that oversized string tokens are rejected before number coercion, and apply wall-clock timeouts to parse and coercion operations. Because matching cost is quadratic in token length, a tight length bound substantially reduces worst-case cost. These are mitigations, not a complete fix.