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CVE-2026-89425 high CVSS 7.5

Vulnerability in com.fasterxml.jackson.core:jackson-core (CVE-2026-89425)

Summary

Vulnerability in com.fasterxml.jackson.core:jackson-core (CVE-2026-89425). Risk of unauthorized operations or information disclosure. Exploitable via StringBuilder. Mitigation: upgrade to 2.18.11 or later.

Original description

The description as published by the source.

Status

FULLY REPRODUCED. A malformed token fed through createParser(DataInput) produced a
20,000,109-character exception message from a 20-million-character attacker payload, while the
identical payload fed through createParser(InputStream) produced a correctly bounded
367-character message.

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/json/UTF8DataInputJsonParser.java
    (_reportInvalidToken(int, String, String), lines ~2763-2780 in the 2.20.2 tree)

Technical Analysis

UTF8DataInputJsonParser._reportInvalidToken() builds the offending-token description for its
exception message by appending identifier characters one at a time to a bare StringBuilder:

protected void _reportInvalidToken(int ch, String matchedPart, String msg) throws IOException {
    StringBuilder sb = new StringBuilder(matchedPart);
    while (true) {
        char c = (char) _decodeCharForError(ch);
        if (!Character.isJavaIdentifierPart(c)) {
            break;
        }
        sb.append(c);
        ch = _inputData.readUnsignedByte();
    }
    _reportError("Unrecognized token '"+sb.toString()+"': was expecting "+msg);
}

There is no check against ErrorReportConfiguration.getMaxErrorTokenLength() (default 256)
anywhere in this loop. By contrast, the sibling UTF8StreamJsonParser implementation of the
same lo…

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-89425 has been found in com.fasterxml.jackson.core:jackson-core.
Attackers can target a specific entry point like StringBuilder over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade com.fasterxml.jackson.core:jackson-core to 2.18.11 or later.
If unsure, ask your IT team or search "com.fasterxml.jackson.core:jackson-core CVE-2026-89425" on the vendor's site.

CVE-2026-89425 (com.fasterxml.jackson.core:jackson-core) — CWE-400 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: StringBuilder / UTF8StreamJsonParser / ReaderBasedJsonParser / NonBlockingUtf8JsonParserBase
Patched: 2.18.11 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-400) exists in com.fasterxml.jackson.core:jackson-core. Attackers reach the vulnerable code path via StringBuilder without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of com.fasterxml.jackson.core:jackson-core. Attack surface: StringBuilder / UTF8StreamJsonParser / ReaderBasedJsonParser / NonBlockingUtf8JsonParserBase.

🔥 Severity

Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 2.18.11.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    Audit SBOM/dependencies for affected components.

    資産台帳・SBOM・依存マニフェストで com.fasterxml.jackson.core:jackson-core を使っているサービスとバージョンを洗い出す。

  2. 2
    Apply patch patch 
    Upgrade com.fasterxml.jackson.core:jackson-core to 2.18.11

    ステージング環境で 2.18.11 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

maven com.fasterxml.jackson.core:jackson-core
[{"type":"ECOSYSTEM","events":[{"introduced":"2.8.0"},{"fixed":"2.18.11"}]}]
maven tools.jackson.core:jackson-core
[{"type":"ECOSYSTEM","events":[{"introduced":"3.2.0"},{"fixed":"3.2.3"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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