CVE-2026-25896 | fast-xml-parser has an entity encoding bypass via regex injection in DOCTYPE entity names

Exp

fast-xml-parser allows users to validate XML, parse XML to JS object, or build XML from JS object without C/C++ based libraries and no callback. From 4.1.3to before 5.3.5, a dot (.) in a DOCTYPE entity name is treated as a regex wildcard during entity replacement, allowing an attacker to shadow built-in XML entities (<, >, &, ", ') with arbitrary values. This bypasses entity encoding and leads to XSS when parsed output is rendered. This vulnerability is fixed in 5.3.5.

Published: 2026-02-20 Last update: 2026-03-02 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-25896 is rated Exploit Available (55.1/100): CVSS Critical severity, with low exploitation likelihood (EPSS 0.03%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2026-25896

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-25896

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-02-21 — 0.03% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-25896

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.3 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 4.7 [email protected]

Weakness enumeration for CVE-2026-25896

GitHub Security Advisory for CVE-2026-25896

GHSA-m7jm-9gc2-mpf2 · Severity: critical · Ecosystem: npm — fast-xml-parser has an entity encoding bypass via regex injection in DOCTYPE entity names

OS Trackers for CVE-2026-25896

vendor priority summary link
debian not yet assigned CVE-2026-25896 not yet assigned priority: Debian including 1 source packages (node-webfont), 4 status rows across 4 suites (bookworm, forky, sid, trixie): undetermined 4. https://security-tracker.debian.org/tracker/CVE-2026-25896
redhat high — https://access.redhat.com/security/cve/CVE-2026-25896
ubuntu medium CVE-2026-25896 medium priority: Ubuntu including 1 source packages (node-webfont), 4 status rows across 4 suites (jammy, noble, questing, upstream): needs-triage 3, DNE 1. https://ubuntu.com/security/CVE-2026-25896

Affected software / configurations for CVE-2026-25896

Vendor Product Version Raw CPE
naturalintelligence fast-xml-parser >= 4.1.3, < 5.3.5 cpe:2.3:a:naturalintelligence:fast-xml-parser:*:*:*:*:*:*:*:*

References for CVE-2026-25896

cvelogic Threat Intelligence