CVE-2021-39229
Regular expression deinal of service in apprise
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. 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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Regular expression deinal of service in apprise
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. 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.
- Record
CVE-2021-39229- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-400
- Updated
- 2026-11-02
EUVDEUVD-2021-0025
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. 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.
- Record
EUVD-2021-0025- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-qhmp-h54x-38qr
Apprise vulnerable to regex injection with IFTTT Plugin
Impact
Anyone publicly hosting the Apprise library and granting them access to the IFTTT notification service.
Patches
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.
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)
- Record
GHSA-qhmp-h54x-38qr- CVSS 4.0
- 8.7 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-400
- Updated
- 2026-11-02
NVD
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. 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.
- Record
CVE-2021-39229- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:N/I:N/A:P - Weakness
- CWE-400
- Updated
- 2026-11-02
OSV
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. 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.
- Record
CVE-2021-39229- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVGHSA-qhmp-h54x-38qr
Apprise vulnerable to regex injection with IFTTT Plugin
Impact
Anyone publicly hosting the Apprise library and granting them access to the IFTTT notification service.
Patches
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.
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)
- Record
GHSA-qhmp-h54x-38qr- CVSS 4.0
- 8.7 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-400
- Updated
- 2026-11-02
OSVPYSEC-2021-327 No score
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. 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.
- Record
PYSEC-2021-327- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
apprisePyPI |
through 0.9.4 | 0.9.5.1 |
apprisePyPI |
before 0.9.5.1, plus listed versions 0.0.10.0.20.0.30.0.40.0.5 Show 28 moreShow less0.0.60.0.70.0.80.0.90.5.00.5.20.7.30.7.40.7.50.7.60.7.70.7.80.7.90.8.00.8.10.8.20.8.30.8.40.8.50.8.60.8.70.8.80.8.90.9.00.9.10.9.20.9.30.9.4 |
0.9.5.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-39229 is a high vulnerability (CVSS 7.5) in Caronc Apprise, published September 20, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.89%, the 79th percentile. Fixed in apprise 0.9.5.1.
References
github.com/caronc/apprise/security/advisories/GHSA-qhmp-h54x-38qr
nvd.nist.gov/vuln/detail/CVE-2021-39229