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Vulnerability record · public intelligence
CVE-2021-41991
UNKNOWN

CVE-2021-41991

Published Oct 18, 2021 · Updated Nov 3, 2026

Severity · CVSSUNKNOWN · Not scored
Known exploitationNot listed
EPSS / likelihood5.30%
QFinch risk scoreNot available

Original summary

Normalized public record · Updated Nov 3, 2026

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.

Publisher and source text is retained separately from QFinch interpretation.

QFinch assessment

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.

Evidence: public source records

Affected products

Affected scope reported by the available public evidence
Affected package, product or rangeFix status
Consult the referenced vendor advisory for affected versions.Consult source advisory

Matching a version is only one part of assessing exposure. QFinch has not assessed your environment on this public page.

Remediation

Apply the vendor-supported fixed release or mitigation, then verify the affected component is no longer reachable.

  1. Confirm the affected product and reachable code path exist in your environment.
  2. Apply the vendor-supported patch or mitigation from the primary advisory.
  3. Rescan the exact deployed revision and retain verification evidence.
Review primary references

Evidence coverage

FIRST-EPSSCVE-LIST-V5
SSVC priority
MEDIUM
Confidence
Not available
Aliases
None reported

Scores appear only when corresponding evidence exists. Missing data is never interpreted as zero risk.

Sources and record history

  1. GitHub advisory ↗
  2. www.strongswan.org ↗
  3. DSA-4989 ↗
  4. [debian-lts-announce] 20211019 [SECURITY] [DLA 2788-1] strongswan security update ↗
  5. FEDORA-2021-0b37146973 ↗
  6. FEDORA-2021-b3df83339e ↗
  7. FEDORA-2021-95fab6a482 ↗
  8. cert-portal.siemens.com ↗

Record history

Published Oct 18, 2021 · Last refreshed Nov 3, 2026

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