Affected: CleanStart: apache-nifi

Security vulnerability affects the apache-nifi package. NumberInput.

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.

Affected: Maven: com.fasterxml.jackson.core:jackson-core, Maven: tools.jackson.core:jackson-core

## Status

**FULLY REPRODUCED** with a clean, textbook empirical signature: measured runtime grew almost exactly 4x for every doubling of input size across five consecutive doublings (5,000 → 160,000 characters), confirming O(n²) behavior. A single 160,000-character string (smaller than a typical HTTP request body) took **74.4 seconds** for one call to `NumberInput.looksLikeValidNumber()`.

## Affected Component / Version

- **Package:** `com.fasterxml.jackson.core:jackson-core` - **Confirmed against:** `jackson-core-2.20.2` - **Affected file:** `src/main/java/com/fasterxml/jackson/core/io/NumberInput.java` (`PATTERN_FLOAT` line ~41-42, `PATTERN_FLOAT_TRAILING_DOT` line ~51, entry point `looksLikeValidNumber()` lines ~646-656)

## Technical Analysis

```java private final static Pattern PATTERN_FLOAT = Pattern.compile( "[+-]?[0-9]*[\\.]?[0-9]+([eE][+-]?[0-9]+)?");

private final static Pattern PATTERN_FLOAT_TRAILING_DOT = Pattern.compile( "[+-]?[0-9]+[\\.]");

public static boolean looksLikeValidNumber(final String s) { // ... short-circuits only for null/empty/length==1 ... return PATTERN_FLOAT.matcher(s).matches() || PATTERN_FLOAT_TRAILING_DOT.matcher(s).matches(); } ```

`PATTERN_FLOAT` contains ambiguous, adjacent quantifiers over the identical character class: `[0-9]*` (optional digits), an optional `[.]`, then `[0-9]+` (required digits). Java's backtracking `Pattern`/`Matcher` engine has no possessive quantifiers or atomic grouping…

jackson-core-2.18.11-1.1 on GA media

Affected: Ubuntu:16.04:LTS: jackson-core, Ubuntu:18.04:LTS: jackson-core, Ubuntu:20.04:LTS: jackson-core, Ubuntu:22.04:LTS: jackson-core, Ubuntu:24.04:LTS: jackson-core, Ubuntu:26.04:LTS: jackson-core

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.

Ein Angreifer kann mehrere Schwachstellen in SOS GmbH JobScheduler ausnutzen, um einen nicht näher spezifizierten Angriff durchzuführen.