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CVE-2021-41991

HIGHCVSS 7.5/10EPSS 4.80%

Last modified

CVE-2021-41991 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. The in-memory certificate cache in strongSwan before 5.9.4 has a remote integer overflow upon receiving many requests with different certificates to fill the cache and later trigger the replacement of cache entries. The code attempts to select a less-often-used cache entry by means of a random number generator, but this is not done correctly. EPSS estimates a 4.80% chance of exploitation in the next 30 days.

Description

The in-memory certificate cache in strongSwan before 5.9.4 has a remote integer overflow upon receiving many requests with different certificates to fill the cache and later trigger the replacement of cache entries. The code attempts to select a less-often-used cache entry by means of a random number generator, but this is not done correctly. Remote code execution might be a slight possibility.

Metrics

CVSS 3.1
7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability
4.80%

90.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
StrongswanStrongswan>= 4.2.10, < 5.9.4
DebianDebian Linux9.0
DebianDebian Linux10.0
DebianDebian Linux11.0
FedoraprojectFedora33
FedoraprojectFedora34
FedoraprojectFedora35
SiemensSinema Remote Connect ServerAll versions
SiemensSiplus Et 200sp Cp 1542sp-1 Irc Tx Rail FirmwareAll versions
SiemensSimatic Cp 1243-1 FirmwareAll versions
SiemensSimatic Cp 1242-7 Gprs V2 FirmwareAll versions
SiemensSimatic Net Cp 1243-8 Irc FirmwareAll versions
SiemensScalance Sc632-2c FirmwareAll versions
SiemensSiplus Et 200sp Cp 1543sp-1 Isec FirmwareAll versions
SiemensCp 1543-1 FirmwareAll versions
SiemensSimatic Net Cp 1545-1 FirmwareAll versions
SiemensSimatic Cp 1543sp-1 FirmwareAll versions
SiemensSimatic Net Cp1243-7 Lte Eu FirmwareAll versions
SiemensSimatic Cp 1243-7 Lte\/Us FirmwareAll versions
SiemensSimatic Cp 1542sp-1 FirmwareAll versions
SiemensScalance Sc636-2c FirmwareAll versions
SiemensSimatic Cp 1542sp-1 Irc FirmwareAll versions
SiemensScalance Sc642-2c FirmwareAll versions
SiemensScalance Sc646-2c Firmware< 2.3
SiemensScalance Sc622-2c FirmwareAll versions
SiemensSiplus S7-1200 Cp 1243-1 Rail FirmwareAll versions
SiemensSiplus S7-1200 Cp 1243-1 FirmwareAll versions
SiemensSiplus Net Cp 1543-1 FirmwareAll versions
SiemensSiplus Et 200sp Cp 1543sp-1 Isec Tx Rail FirmwareAll versions

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

What is CVE-2021-41991?
The in-memory certificate cache in strongSwan before 5.9.4 has a remote integer overflow upon receiving many requests with different certificates to fill the cache and later trigger the replacement of cache entries. The code attempts to select a less-often-used cache entry by means of a random number generator, but this is not done correctly. Remote code execution might be a slight possibility.
How severe is CVE-2021-41991?
CVE-2021-41991 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 4.80% probability of exploitation in the next 30 days.
How do I fix CVE-2021-41991?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-41991?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST