CVE-2021-4249 xml-conduit DOCTYPE Entity Expansion Parse.hs infinite loop
Remote attackers can cause a denial of service via an infinite loop in the DOCTYPE entity expansion handler of the xml-conduit library.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2021-4249?
CVE-2021-4249 is a medium-severity denial of service vulnerability in unspecified xml-conduit, published on 18 Dec 2022. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
A vulnerability was found in xml-conduit. It has been classified as problematic. Affected is an unknown function of the file xml-conduit/src/Text/XML/Stream/Parse.hs of the component DOCTYPE Entity Expansion Handler. The manipulation leads to infinite loop. It is possible to launch the attack remotely. Upgrading to version 1.9.1.0 is able to address this issue. The name of the patch is 4be1021791dcdee8b164d239433a2043dc0939ea. It is recommended to upgrade the affected component. The identifier of this vulnerability is VDB-216204.
Weakness: CWE-404
Which versions are affected by CVE-2021-4249?
1 open source package ship an affected version, including xml-conduit. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
xml-conduit Hackage | From 0.5.0 | 1.9.1.0 |
Linux distribution packages (1)
ghc-xml-conduit openSUSE:Tumbleweed | All versions | 1.10.1.0-2.1 |
Products include Haskell Xml-Conduit.
How do I fix CVE-2021-4249?
Upgrade xml-conduit to 1.9.1.0 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2021-4249 being exploited?
There is no known exploitation of CVE-2021-4249 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2021-4249, GHSA-r5mv-3cq3-727q, HSEC-2023-0004, UBUNTU-CVE-2021-4249, openSUSE-SU-2026:11086-1.