CVE-2021-39229 Regular expression deinal of service in apprise
Attackers can cause denial of service in the Apprise library via inefficient regular expressions in the IFTTT plugin, affecting users sending notifications.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-39229?
CVE-2021-39229 is a high-severity denial of service vulnerability in caronc apprise, published on 20 Sep 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Apprise is an open source library which allows you to send a notification to almost all of the most popular notification services available. In affected versions users who use Apprise granting them access to the IFTTT plugin (which just comes out of the box) are subject to a denial of service attack on an inefficient regular expression. The vulnerable regular expression is [here](https://github.com/caronc/apprise/blob/0007eade20934ddef0aba38b8f1aad980cfff253/apprise/plugins/NotifyIFTTT.py#L356-L359). The problem has been patched in release version 0.9.5.1. Users who are unable to upgrade are advised to remove `apprise/plugins/NotifyIFTTT.py` to eliminate the service.
Weakness: CWE-400
Which versions are affected by CVE-2021-39229?
3 open source packages ship an affected version, including apprise. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
apprise PyPI | All versions | 0.9.5.1 |
apprise PyPI | All versions | 0.9.5.1 |
apprise PyPI | All versions | 0.9.5.1 |
Products include Nuxref Apprise.
How do I fix CVE-2021-39229?
Upgrade apprise to 0.9.5.1 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-2021-39229 being exploited?
There is no known exploitation of CVE-2021-39229 in the wild and no public exploit code.
Sources
Also known as GHSA-qhmp-h54x-38qr, PYSEC-2021-327.