CVE-2021-41991
charon-cmd: The in-memory certificate cache in strongSwan before 5.9.4 has a remoteinteger overflow upon receiving many requests...
CVE-2021-41991 is fixed in 21 products on 1 platform, first by charon-cmd 5.6.2-1ubuntu2.7, released October 18, 2021. It is not reported as exploited. Patch Radar priority: Routine.
Routine
CVSS
n/a
Medium
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0530
92nd percentile
The in-memory certificate cache in strongSwan before 5.9.4 has a remoteinteger overflow upon receiving many requests with different certificatesto fill the cache and later trigger the replacement of cache entries. Thecode attempts to select a less-often-used cache entry by means of a randomnumber generator, but this is not done correctly. Remote code executionmight be a slight possibility.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| charon-cmd · Ubuntu 18.04.6 LTS (bionic) | 5.6.2-1ubuntu2.7 | charon-cmd 5.6.2-1ubuntu2.7 | Oct 18, 2021 |
| charon-cmd · Ubuntu 20.04 LTS (focal) | 5.8.2-1ubuntu3.3 | charon-cmd 5.8.2-1ubuntu3.3 | Oct 18, 2021 |
| charon-cmd · Ubuntu 22.04.1 LTS (jammy) | 5.9.1-1ubuntu3.1 | charon-cmd 5.9.1-1ubuntu3.1 | Oct 18, 2021 |
| charon-cmd · Ubuntu 24.10 (oracular) | 5.9.1-1ubuntu3.1 | charon-cmd 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| charon-cmd · Ubuntu 25.04 (plucky) | 5.9.1-1ubuntu3.1 | charon-cmd 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| charon-systemd · Ubuntu 18.04.6 LTS (bionic) | 5.6.2-1ubuntu2.7 | charon-systemd 5.6.2-1ubuntu2.7 | Oct 18, 2021 |
| charon-systemd · Ubuntu 20.04 LTS (focal) | 5.8.2-1ubuntu3.3 | charon-systemd 5.8.2-1ubuntu3.3 | Oct 18, 2021 |
| charon-systemd · Ubuntu 22.04.1 LTS (jammy) | 5.9.1-1ubuntu3.1 | charon-systemd 5.9.1-1ubuntu3.1 | Oct 18, 2021 |
| charon-systemd · Ubuntu 24.10 (oracular) | 5.9.1-1ubuntu3.1 | charon-systemd 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| charon-systemd · Ubuntu 25.04 (plucky) | 5.9.1-1ubuntu3.1 | charon-systemd 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| libcharon-extauth-plugins · Ubuntu 20.04 LTS (focal) | 5.8.2-1ubuntu3.3 | libcharon-extauth-plugins 5.8.2-1ubuntu3.3 | Oct 18, 2021 |
| libcharon-extauth-plugins · Ubuntu 22.04.1 LTS (jammy) | 5.9.1-1ubuntu3.1 | libcharon-extauth-plugins 5.9.1-1ubuntu3.1 | Oct 18, 2021 |
| libcharon-extauth-plugins · Ubuntu 24.10 (oracular) | 5.9.1-1ubuntu3.1 | libcharon-extauth-plugins 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| libcharon-extauth-plugins · Ubuntu 25.04 (plucky) | 5.9.1-1ubuntu3.1 | libcharon-extauth-plugins 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| libcharon-extra-plugins · Ubuntu 18.04.6 LTS (bionic) | 5.6.2-1ubuntu2.7 | libcharon-extra-plugins 5.6.2-1ubuntu2.7 | Oct 18, 2021 |
| libcharon-extra-plugins · Ubuntu 20.04 LTS (focal) | 5.8.2-1ubuntu3.3 | libcharon-extra-plugins 5.8.2-1ubuntu3.3 | Oct 18, 2021 |
| libcharon-extra-plugins · Ubuntu 22.04.1 LTS (jammy) | 5.9.1-1ubuntu3.1 | libcharon-extra-plugins 5.9.1-1ubuntu3.1 | Oct 18, 2021 |
| libcharon-extra-plugins · Ubuntu 24.10 (oracular) | 5.9.1-1ubuntu3.1 | libcharon-extra-plugins 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| libcharon-extra-plugins · Ubuntu 25.04 (plucky) | 5.9.1-1ubuntu3.1 | libcharon-extra-plugins 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| libcharon-standard-plugins · Ubuntu 18.04.6 LTS (bionic) | 5.6.2-1ubuntu2.7 | libcharon-standard-plugins 5.6.2-1ubuntu2.7 | Oct 18, 2021 |
| libcharon-standard-plugins · Ubuntu 20.04 LTS (focal) | 5.8.2-1ubuntu3.3 | libcharon-standard-plugins 5.8.2-1ubuntu3.3 | Oct 18, 2021 |
| libstrongswan · Ubuntu 18.04.6 LTS (bionic) | 5.6.2-1ubuntu2.7 | libstrongswan 5.6.2-1ubuntu2.7 | Oct 18, 2021 |
| libstrongswan · Ubuntu 20.04 LTS (focal) | 5.8.2-1ubuntu3.3 | libstrongswan 5.8.2-1ubuntu3.3 | Oct 18, 2021 |
| libstrongswan · Ubuntu 22.04.1 LTS (jammy) | 5.9.1-1ubuntu3.1 | libstrongswan 5.9.1-1ubuntu3.1 | Oct 18, 2021 |
| libstrongswan · Ubuntu 24.10 (oracular) | 5.9.1-1ubuntu3.1 | libstrongswan 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| libstrongswan · Ubuntu 25.04 (plucky) | 5.9.1-1ubuntu3.1 | libstrongswan 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| libstrongswan-extra-plugins · Ubuntu 18.04.6 LTS (bionic) | 5.6.2-1ubuntu2.7 | libstrongswan-extra-plugins 5.6.2-1ubuntu2.7 | Oct 18, 2021 |
| libstrongswan-extra-plugins · Ubuntu 20.04 LTS (focal) | 5.8.2-1ubuntu3.3 | libstrongswan-extra-plugins 5.8.2-1ubuntu3.3 | Oct 18, 2021 |
| libstrongswan-extra-plugins · Ubuntu 22.04.1 LTS (jammy) | 5.9.1-1ubuntu3.1 | libstrongswan-extra-plugins 5.9.1-1ubuntu3.1 | Oct 18, 2021 |
| libstrongswan-extra-plugins · Ubuntu 24.10 (oracular) | 5.9.1-1ubuntu3.1 | libstrongswan-extra-plugins 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| libstrongswan-extra-plugins · Ubuntu 25.04 (plucky) | 5.9.1-1ubuntu3.1 | libstrongswan-extra-plugins 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| libstrongswan-standard-plugins · Ubuntu 18.04.6 LTS (bionic) | 5.6.2-1ubuntu2.7 | libstrongswan-standard-plugins 5.6.2-1ubuntu2.7 | Oct 18, 2021 |
| libstrongswan-standard-plugins · Ubuntu 20.04 LTS (focal) | 5.8.2-1ubuntu3.3 | libstrongswan-standard-plugins 5.8.2-1ubuntu3.3 | Oct 18, 2021 |
| libstrongswan-standard-plugins · Ubuntu 22.04.1 LTS (jammy) | 5.9.1-1ubuntu3.1 | libstrongswan-standard-plugins 5.9.1-1ubuntu3.1 | Oct 18, 2021 |
| libstrongswan-standard-plugins · Ubuntu 24.10 (oracular) | 5.9.1-1ubuntu3.1 | libstrongswan-standard-plugins 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| libstrongswan-standard-plugins · Ubuntu 25.04 (plucky) | 5.9.1-1ubuntu3.1 | libstrongswan-standard-plugins 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| strongswan · Ubuntu 18.04.6 LTS (bionic) | 5.6.2-1ubuntu2.7 | strongswan 5.6.2-1ubuntu2.7 | Oct 18, 2021 |
| strongswan · Ubuntu 20.04 LTS (focal) | 5.8.2-1ubuntu3.3 | strongswan 5.8.2-1ubuntu3.3 | Oct 18, 2021 |
| strongswan · Ubuntu 22.04.1 LTS (jammy) | 5.9.1-1ubuntu3.1 | strongswan 5.9.1-1ubuntu3.1 | Oct 18, 2021 |
| strongswan · Ubuntu 24.10 (oracular) | 5.9.1-1ubuntu3.1 | strongswan 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| strongswan · Ubuntu 25.04 (plucky) | 5.9.1-1ubuntu3.1 | strongswan 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| strongswan-charon · Ubuntu 18.04.6 LTS (bionic) | 5.6.2-1ubuntu2.7 | strongswan-charon 5.6.2-1ubuntu2.7 | Oct 18, 2021 |
| strongswan-charon · Ubuntu 20.04 LTS (focal) | 5.8.2-1ubuntu3.3 | strongswan-charon 5.8.2-1ubuntu3.3 | Oct 18, 2021 |
| strongswan-charon · Ubuntu 22.04.1 LTS (jammy) | 5.9.1-1ubuntu3.1 | strongswan-charon 5.9.1-1ubuntu3.1 | Oct 18, 2021 |
| strongswan-charon · Ubuntu 24.10 (oracular) | 5.9.1-1ubuntu3.1 | strongswan-charon 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| strongswan-charon · Ubuntu 25.04 (plucky) | 5.9.1-1ubuntu3.1 | strongswan-charon 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| strongswan-libcharon · Ubuntu 18.04.6 LTS (bionic) | 5.6.2-1ubuntu2.7 | strongswan-libcharon 5.6.2-1ubuntu2.7 | Oct 18, 2021 |
| strongswan-libcharon · Ubuntu 20.04 LTS (focal) | 5.8.2-1ubuntu3.3 | strongswan-libcharon 5.8.2-1ubuntu3.3 | Oct 18, 2021 |
| strongswan-libcharon · Ubuntu 22.04.1 LTS (jammy) | 5.9.1-1ubuntu3.1 | strongswan-libcharon 5.9.1-1ubuntu3.1 | Oct 18, 2021 |
| strongswan-libcharon · Ubuntu 24.10 (oracular) | 5.9.1-1ubuntu3.1 | strongswan-libcharon 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| strongswan-libcharon · Ubuntu 25.04 (plucky) | 5.9.1-1ubuntu3.1 | strongswan-libcharon 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| strongswan-nm · Ubuntu 18.04.6 LTS (bionic) | 5.6.2-1ubuntu2.7 | strongswan-nm 5.6.2-1ubuntu2.7 | Oct 18, 2021 |
| strongswan-nm · Ubuntu 20.04 LTS (focal) | 5.8.2-1ubuntu3.3 | strongswan-nm 5.8.2-1ubuntu3.3 | Oct 18, 2021 |
| strongswan-nm · Ubuntu 22.04.1 LTS (jammy) | 5.9.1-1ubuntu3.1 | strongswan-nm 5.9.1-1ubuntu3.1 | Oct 18, 2021 |
| strongswan-nm · Ubuntu 24.10 (oracular) | 5.9.1-1ubuntu3.1 | strongswan-nm 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| strongswan-nm · Ubuntu 25.04 (plucky) | 5.9.1-1ubuntu3.1 | strongswan-nm 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| strongswan-pki · Ubuntu 18.04.6 LTS (bionic) | 5.6.2-1ubuntu2.7 | strongswan-pki 5.6.2-1ubuntu2.7 | Oct 18, 2021 |
| strongswan-pki · Ubuntu 20.04 LTS (focal) | 5.8.2-1ubuntu3.3 | strongswan-pki 5.8.2-1ubuntu3.3 | Oct 18, 2021 |
| strongswan-pki · Ubuntu 22.04.1 LTS (jammy) | 5.9.1-1ubuntu3.1 | strongswan-pki 5.9.1-1ubuntu3.1 | Oct 18, 2021 |
| strongswan-pki · Ubuntu 24.10 (oracular) | 5.9.1-1ubuntu3.1 | strongswan-pki 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| strongswan-pki · Ubuntu 25.04 (plucky) | 5.9.1-1ubuntu3.1 | strongswan-pki 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| strongswan-scepclient · Ubuntu 18.04.6 LTS (bionic) | 5.6.2-1ubuntu2.7 | strongswan-scepclient 5.6.2-1ubuntu2.7 | Oct 18, 2021 |
| strongswan-scepclient · Ubuntu 20.04 LTS (focal) | 5.8.2-1ubuntu3.3 | strongswan-scepclient 5.8.2-1ubuntu3.3 | Oct 18, 2021 |
| strongswan-scepclient · Ubuntu 22.04.1 LTS (jammy) | 5.9.1-1ubuntu3.1 | strongswan-scepclient 5.9.1-1ubuntu3.1 | Oct 18, 2021 |
| strongswan-starter · Ubuntu 18.04.6 LTS (bionic) | 5.6.2-1ubuntu2.7 | strongswan-starter 5.6.2-1ubuntu2.7 | Oct 18, 2021 |
| strongswan-starter · Ubuntu 20.04 LTS (focal) | 5.8.2-1ubuntu3.3 | strongswan-starter 5.8.2-1ubuntu3.3 | Oct 18, 2021 |
| strongswan-starter · Ubuntu 22.04.1 LTS (jammy) | 5.9.1-1ubuntu3.1 | strongswan-starter 5.9.1-1ubuntu3.1 | Oct 18, 2021 |
| strongswan-starter · Ubuntu 24.10 (oracular) | 5.9.1-1ubuntu3.1 | strongswan-starter 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| strongswan-starter · Ubuntu 25.04 (plucky) | 5.9.1-1ubuntu3.1 | strongswan-starter 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| strongswan-swanctl · Ubuntu 18.04.6 LTS (bionic) | 5.6.2-1ubuntu2.7 | strongswan-swanctl 5.6.2-1ubuntu2.7 | Oct 18, 2021 |
| strongswan-swanctl · Ubuntu 20.04 LTS (focal) | 5.8.2-1ubuntu3.3 | strongswan-swanctl 5.8.2-1ubuntu3.3 | Oct 18, 2021 |
| strongswan-swanctl · Ubuntu 22.04.1 LTS (jammy) | 5.9.1-1ubuntu3.1 | strongswan-swanctl 5.9.1-1ubuntu3.1 | Oct 18, 2021 |
| strongswan-swanctl · Ubuntu 24.10 (oracular) | 5.9.1-1ubuntu3.1 | strongswan-swanctl 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| strongswan-swanctl · Ubuntu 25.04 (plucky) | 5.9.1-1ubuntu3.1 | strongswan-swanctl 5.9.1-1ubuntu3.1 | Jan 16, 2026 |
| strongswan-tnc-base · Ubuntu 18.04.6 LTS (bionic) | 5.6.2-1ubuntu2.7 | strongswan-tnc-base 5.6.2-1ubuntu2.7 | Oct 18, 2021 |
| strongswan-tnc-base · Ubuntu 20.04 LTS (focal) | 5.8.2-1ubuntu3.3 | strongswan-tnc-base 5.8.2-1ubuntu3.3 | Oct 18, 2021 |
| strongswan-tnc-client · Ubuntu 18.04.6 LTS (bionic) | 5.6.2-1ubuntu2.7 | strongswan-tnc-client 5.6.2-1ubuntu2.7 | Oct 18, 2021 |
| strongswan-tnc-client · Ubuntu 20.04 LTS (focal) | 5.8.2-1ubuntu3.3 | strongswan-tnc-client 5.8.2-1ubuntu3.3 | Oct 18, 2021 |
| strongswan-tnc-ifmap · Ubuntu 18.04.6 LTS (bionic) | 5.6.2-1ubuntu2.7 | strongswan-tnc-ifmap 5.6.2-1ubuntu2.7 | Oct 18, 2021 |
| strongswan-tnc-ifmap · Ubuntu 20.04 LTS (focal) | 5.8.2-1ubuntu3.3 | strongswan-tnc-ifmap 5.8.2-1ubuntu3.3 | Oct 18, 2021 |
| strongswan-tnc-pdp · Ubuntu 18.04.6 LTS (bionic) | 5.6.2-1ubuntu2.7 | strongswan-tnc-pdp 5.6.2-1ubuntu2.7 | Oct 18, 2021 |
| strongswan-tnc-pdp · Ubuntu 20.04 LTS (focal) | 5.8.2-1ubuntu3.3 | strongswan-tnc-pdp 5.8.2-1ubuntu3.3 | Oct 18, 2021 |
| strongswan-tnc-server · Ubuntu 18.04.6 LTS (bionic) | 5.6.2-1ubuntu2.7 | strongswan-tnc-server 5.6.2-1ubuntu2.7 | Oct 18, 2021 |
| strongswan-tnc-server · Ubuntu 20.04 LTS (focal) | 5.8.2-1ubuntu3.3 | strongswan-tnc-server 5.8.2-1ubuntu3.3 | Oct 18, 2021 |
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