CVE-2020-5227Network attack vector

Service interruption via recursive XML entity expansion

Published Jan 28, 2020 · Updated Aug 4, 2024

XML entity expansion in Feedgen before 0.9.0 allows attackers to interrupt feed generation by supplying crafted XML content. The _add_text_elm path passes XML and XHTML field values to lxml.etree.fromstring with entity resolution enabled, allowing recursive entities to exhaust resources. Reachability requires a consuming application to pass attacker-controlled XML rather than plain text; the documented consequence is denial of service.

CVSS severity4.4
Medium
EPSS probability2.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

XML entity expansion in Feedgen before 0.9.0 allows attackers to interrupt feed generation by supplying crafted XML content. The _add_text_elm path passes XML and XHTML field values to lxml.etree.fromstring with entity resolution enabled, allowing recursive entities to exhaust resources. Reachability requires a consuming application to pass attacker-controlled XML rather than plain text; the documented consequence is denial of service.

The record

CVE
CVE-2020-5227
Published
Jan 28, 2020
Updated
Aug 4, 2024
Vendor
Lars Kiesow
Product
Feedgen
Classifications
CWE-776, T1499.004
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Jan 28, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.9.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Lars Kiesow · Feedgenversion=< 0.9.0

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
4.4GitHubCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-776Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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