CVE intelligence and bounded remediation

CVE-2021-39229 — Apprise is an open source library which allows you to send a notification to almost all of the most popular notification services available

High CVSS 7.5

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.

Severity
High
CVSS
7.5 (3.1)
Published
2021-09-20
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-400

Affected products

  • nuxref / apprise

Matched remediation archetype

Resource exhaustion and denial of service

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Identify attacker-influenced work factors including input size, nesting, compression, fan-out, regex cost, allocation, recursion, retries, and connection lifetime.
  • Map per-request and shared CPU, memory, disk, descriptor, thread, queue, and downstream-service limits.
  • Determine whether authentication, tenancy, quotas, and rate controls apply before expensive processing begins.

Remediate safely

  • Bound input size, nesting, expansion, work, concurrency, queue depth, retries, and execution time before resource-intensive processing.
  • Release resources on every success, error, cancellation, and timeout path and use backpressure instead of unbounded buffering.
  • Update affected components and add small deterministic tests that assert resource ceilings rather than exhausting a host.

Authoritative sources

Complete CVE record and remediation plan

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