What is CVE-2021-39229?

CVE-2021-39229 is a high-severity uncontrolled resource consumption vulnerability in apprise (pip), affecting versions <= 0.9.4. It is fixed in 0.9.5.1. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.

How severe is CVE-2021-39229?

CVE-2021-39229 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.

Which versions of apprise are affected by CVE-2021-39229?

apprise (pip) versions <= 0.9.4 is affected.

Is there a fix for CVE-2021-39229?

Yes. CVE-2021-39229 is fixed in 0.9.5.1. Upgrade to this version or later.

Is CVE-2021-39229 exploitable, and should I be worried?

Whether CVE-2021-39229 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

What actually determines whether CVE-2021-39229 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

How do I fix CVE-2021-39229?

Upgrade apprise to 0.9.5.1 or later.

CVE-2021-39229 in apprise

Q: How severe is CVE-2021-39229?

CVE-2021-39229 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.

Q: Which versions of apprise are affected by CVE-2021-39229?

apprise (pip) versions <= 0.9.4 is affected.

Q: Is there a fix for CVE-2021-39229?

Yes. CVE-2021-39229 is fixed in 0.9.5.1. Upgrade to this version or later.

Q: Is CVE-2021-39229 exploitable, and should I be worried?

Whether CVE-2021-39229 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

Q: What actually determines whether CVE-2021-39229 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

Q: How do I fix CVE-2021-39229?

Upgrade apprise to 0.9.5.1 or later.

Summary

Apprise vulnerable to regex injection with IFTTT Plugin

Workarounds

Alternatively, if upgrading is not an option, you can safely remove the following file:

apprise/plugins/NotifyIFTTT.py

The above will eliminate the ability to use IFTTT, but everything else will work smoothly.

For more information

If you have any questions or comments about this advisory:

Open an issue in Apprise
Email me at [email protected]

Additional Credit

Github would not allow me to additionally credit Rasmus Petersen, but I would like to put that here at the very least - thank you for finding and reporting this issue along with those already credited

Additional Notes:

Github would not allow me to add/tag the 2 CWE's this issue is applicable to (only CWE-400). The other is: CWE-730 (placed in the title)

Impact

Anyone publicly hosting the Apprise library and granting them access to the IFTTT notification service.

Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.

CVE-2021-39229 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.9.5.1); upgrading removes the vulnerable code path.

Affected versions

apprise (<= 0.9.4)

Security releases

apprise → 0.9.5.1 (pip)

Kodem intelligence

Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.

Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.

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Remediation advice

Update to Apprise v0.9.5.1

# Install Apprise v0.9.5.1 from PyPI
pip install apprise==0.9.5.1

The patch to the problem was performed here.

Frequently Asked Questions

What is CVE-2021-39229? CVE-2021-39229 is a high-severity uncontrolled resource consumption vulnerability in apprise (pip), affecting versions <= 0.9.4. It is fixed in 0.9.5.1. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
How severe is CVE-2021-39229? CVE-2021-39229 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
Which versions of apprise are affected by CVE-2021-39229? apprise (pip) versions <= 0.9.4 is affected.
Is there a fix for CVE-2021-39229? Yes. CVE-2021-39229 is fixed in 0.9.5.1. Upgrade to this version or later.
Is CVE-2021-39229 exploitable, and should I be worried? Whether CVE-2021-39229 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
What actually determines whether CVE-2021-39229 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
How do I fix CVE-2021-39229? Upgrade apprise to 0.9.5.1 or later.