CVE-2009-2473: neon before 0.28.6, when expat is used, does not properly detect recursion during entity expansion, which allo

This week

MEDIUM 4.3DOWNGRADE

CVE-2009-2473 is a medium-severity flaw (CVSS 4.3) affecting neon. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

neon before 0.28.6, when expat is used, does not properly detect recursion during entity expansion, which allows context-dependent attackers to cause a denial of service (memory and CPU consumption) via a crafted XML document containing a large number of nested entity references, a similar issue to CVE-2003-1564.

Why this priority

EPSS top 5%: very likely to be exploited
Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	4.3 (Medium)
EPSS exploit chance	8.4% (top 5%)
CISA exploited list	No
Weakness	CWE-399
Published	2009-08-21
Last modified	2026-06-16

Publisher (CNA): Red Hat, Inc. · Vendor: webdav

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2009-08-21 17:30 UTCPublished CVE record published
2026-06-16 23:09 UTCUpdated Record last modified

webdav neon DOWNGRADE

Affected: 0.28.6

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.28.6

1. Check installed version

apt-cache policy neon || rpm -q neon || neon --version

2. No fixed release: DOWNGRADE to a release before 0.28.6 (Debian / Ubuntu)

apt-cache madison neon sudo apt install neon=<VERSION_BEFORE_0.28.6> sudo apt-mark hold neon

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list neon sudo dnf downgrade neon-<VERSION_BEFORE_0.28.6> sudo dnf versionlock add neon

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Exploit-DB: Expat 2.0.1 - UTF-8 Character XML Parsing Remote Denial of Service

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2009-2473?

neon: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2009-2473 being exploited?

CVE-2009-2473 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2009-2473 affect?

CVE-2009-2473 affects neon. Severity is medium (CVSS 4.3). neon before 0.28.6, when expat is used, does not properly detect recursion during entity expansion, which allows context-dependent attackers to cause a denial of service (memory and CPU consumption) via a crafted XML document containing a l

How urgent is CVE-2009-2473?

Priority 44/100. EPSS top 5%: very likely to be exploited; Public exploit reference

Related CVEs

CVE-2020-23576 MEDIUM 5.4 DOWNGRADE Laborator Neon dashboard v3 is affected by stored Cross Site Scripting (XSS) via the chat tab.
CVE-2020-13890 MEDIUM 5.4 UPGRADE The Neon theme 2.0 before 2020-06-03 for Bootstrap allows XSS via an Add Task Input operation in a dashboard.
CVE-2019-20141 MEDIUM 6.1 DOWNGRADE An XSS issue was discovered in the Laborator Neon theme 2.0 for WordPress via the data/autosuggest-remote.php
CVE-2009-2474 MEDIUM 5.8 UPGRADE UPGRADE neon before 0.28.6, when OpenSSL or GnuTLS is used, does not properly handle a '\0' character in a domain name
CVE-2008-3746 MEDIUM 4.3 DOWNGRADE neon 0.28.0 through 0.28.2 allows remote servers to cause a denial of service (NULL pointer dereference and cr

References

← Back to latest CVEs