CVE-2026-66293

XML comment injection in Saxy encoder via unescaped double hyphen

Published Nov 6, 2026 CVSS 4.0 · 2.1 Low EPSS < 1% KEV · Not listed
Description
XML injection in the encoder of Saxy. Saxy.Encoder does not neutralize the -- sequence in XML comment content: escape_comment/2 returns the comment binary unchanged in every clause and only appends a space when the comment ends in a single -, so neither an interior -- nor a full --> is escaped or rejected before the encoder wraps the content in the <!-- and --> delimiters.

When an application serializes attacker-controlled text as a comment, through Saxy.XML.comment/1 or a raw {:comment, text} simple form child, the attacker can close the comment early with --> and inject arbitrary sibling markup into the serialized document. A downstream parser then sees elements, attributes, and text that the application never built. Where the document is rendered as HTML or SVG, the injected markup executes as stored cross-site scripting; where it is consumed by another XML processor, the attacker can forge data that the producing application never emitted. Documents that Saxy only parses are not a vector.

This issue affects saxy: from 0.7.0 before 1.7.0.

Remediation

Vendor Workaround

Reject or rewrite the -- sequence in untrusted text before passing it to Saxy.XML.comment/1, for example by replacing -- with - -. Alternatively, stop emitting untrusted data as XML comments. Comments carry no semantic payload for consumers, so the text can usually be moved into an element or a CDATA section instead.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description XML injection in the encoder of Saxy. Saxy.Encoder does not neutralize the -- sequence in XML comment content: escape_comment/2 returns the comment binary unchanged in every clause and only appends a space when the comment ends in a single -, so neither an interior -- nor a full --> is escaped or rejected before the encoder wraps the content in the <!-- and --> delimiters. When an application serializes attacker-controlled text as a comment, through Saxy.XML.comment/1 or a raw {:comment, text} simple form child, the attacker can close the comment early with --> and inject arbitrary sibling markup into the serialized document. A downstream parser then sees elements, attributes, and text that the application never built. Where the document is rendered as HTML or SVG, the injected markup executes as stored cross-site scripting; where it is consumed by another XML processor, the attacker can forge data that the producing application never emitted. Documents that Saxy only parses are not a vector. This issue affects saxy: from 0.7.0 before 1.7.0.
Title XML comment injection in Saxy encoder via unescaped double hyphen
First Time appeared Qcam
Qcam saxy
Weaknesses CWE-91
CPEs cpe:2.3:a:qcam:saxy:*:*:*:*:*:*:*:*
Vendors & Products Qcam
Qcam saxy
References
Metrics cvssV4_0

{'score': 2.1, 'vector': 'CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
EEF
Published
Updated
Nov 10, 2026, 5:42 PM
Reserved
Jul 24, 2026, 2:10 PM
Status
Deferred
Published
Nov 6, 2026, 11:17 AM
Modified
Nov 12, 2026, 8:07 PM