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Fencer Vulns
low 2.1

CVE-2026-66294 json

XML injection in Saxy via unescaped CDATA section terminator

published 2026-11-06 2 d ago modified 2026-11-06 2 d ago also EEF-CVE-2026-66294 , GHSA-hq6g-j46w-wx72 , EUVD-2026-118039

cvss
2.1
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 6%
public exploits
0
none known

Summary

XML injection in the Saxy XML encoder. Saxy.Encoder.cdata/1 serializes a {:cdata, characters} node by wrapping the supplied characters between <![CDATA[ and ]]> and passing the payload through byte for byte. The encoder's character-data and attribute-value paths escape the XML metacharacters <, >, &, ", and ', but the CDATA path applies no neutralization at all. XML provides no character escaping mechanism inside a CDATA section, so the only correct way to represent a ]]> substring is to split the section and rejoin it as ]]]]><![CDATA[>. Saxy neither performs that split nor rejects the substring.

An application that renders untrusted text as CDATA, by building the node with Saxy.XML.cdata/1 and serializing it with Saxy.encode!/2 or Saxy.encode_to_iodata!/2, therefore lets an attacker terminate the section at a position of their choosing. Everything supplied after the ]]> is emitted outside any CDATA context and is parsed as markup, so a single attacker-controlled text field becomes attacker-controlled document structure: arbitrary sibling elements and attributes that the application never built. Downstream consumers of the serialized document accept the injected markup as genuine. Services that generate SOAP envelopes, RSS or Atom feeds, sitemaps, SVG, or XML exports from user-supplied content can have trusted fields forged or overridden. Applications that never place untrusted text in a CDATA node are not affected.

This issue affects saxy: from 0.7.0 before 1.7.0.

Patch / fix

  • hex saxy 1.7.0
  • qcam saxy 1.7.0

Exploit prediction

0.17% chance of exploitation in the next 30 days, higher than 6% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 2.1 CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N
CNA 4.0 2.1 CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected packages

ecosystem package affected fixed in
hex saxy
>=0.7.0, <1.7.0
1.7.0

Affected products

  • qcam saxy

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.