Remote denial of service via MQTT pointer reuse
Published Sep 23, 2021 · Updated Jun 9, 2025
Double-free vulnerability in curl libcurl 7.73.0 through 7.78.0 allows remote attackers to cause denial of service via MQTT data sending. While sending MQTT data, libcurl retains a pointer after freeing its memory and reuses and frees that pointer again on a later send. Exploitation requires an MQTT transfer reaching the flawed path and can crash the curl process; the advisory reports no known exploitation in the wild.
Summary
What happened
Double-free vulnerability in curl libcurl 7.73.0 through 7.78.0 allows remote attackers to cause denial of service via MQTT data sending. While sending MQTT data, libcurl retains a pointer after freeing its memory and reuses and frees that pointer again on a later send. Exploitation requires an MQTT transfer reaching the flawed path and can crash the curl process; the advisory reports no known exploitation in the wild.
The record
- CVE
- CVE-2021-22945
- Published
- Sep 23, 2021
- Updated
- Jun 9, 2025
- Vendor
- curl
- Product
- curl
- Classifications
- CWE-415, T1203
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 23, 2021CVE publishedPublication date reported by the CVE source.
- Jun 9, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=curl 7.73.0 to and including 7.78.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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