Saxy's XML encoder writes the target and the content of a processing instruction into the output document verbatim, without validation or escaping. The encoder builds the construct by concatenating both fields between , so neither field is checked against the constraints the XML specification places on it.
Because ?> terminates a processing instruction, a target or content value containing that sequence closes the construct at a position the attacker chooses. Everything the attacker writes after it is emitted as ordinary markup at document level, which allows arbitrary elements, attributes, and further processing instructions to be injected into the serialized document. Appending a matching
The result is XML injection into a serialized document: the tree the application asks Saxy to encode and the tree a downstream parser reads back are no longer the same. Character data, attribute values, and comments are all escaped by the encoder, so processing instructions are the one construct that passes user bytes through untouched. Since Saxy.XML.processing_instruction/2 is a documented public builder, an application inherits the flaw without misusing the API. The consequences depend on what consumes the XML: forged records in a feed or export read by another system, injected stylesheet or rendering directives, or active content where the output is served to a browser as XML or SVG.
This issue affects saxy: from 0.7.0 before 1.7.0.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (2.1): severity, escalated by confirmed exploitation. This CVE's 2.1 is its impact severity (EG Severity), not escalated.
- EG Severity
- 2.1 LOWCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source
- EG Likelihood
- 0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-12). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.
A fix is available. Apply it within your standard update timelines.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it