High severity7.5NVD Advisory· Published Oct 18, 2021· Updated Jun 17, 2026
CVE-2021-41991
CVE-2021-41991
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.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected products
36- strongSwan/strongSwandescription
- Range: <5.9.4
- osv-coords34 versionspkg:rpm/opensuse/strongswan&distro=openSUSE%20Leap%2015.2pkg:rpm/opensuse/strongswan&distro=openSUSE%20Leap%2015.3pkg:rpm/opensuse/strongswan&distro=openSUSE%20Tumbleweedpkg:rpm/suse/strongswan&distro=HPE%20Helion%20OpenStack%208pkg:rpm/suse/strongswan&distro=SUSE%20Enterprise%20Storage%206pkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20High%20Performance%20Computing%2015%20SP1-ESPOSpkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20High%20Performance%20Computing%2015%20SP1-LTSSpkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20High%20Performance%20Computing%2015-ESPOSpkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20High%20Performance%20Computing%2015-LTSSpkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20Module%20for%20Basesystem%2015%20SP2pkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20Module%20for%20Basesystem%2015%20SP3pkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20Module%20for%20Package%20Hub%2015%20SP2pkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20Module%20for%20Package%20Hub%2015%20SP3pkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20Point%20of%20Sale%2011%20SP3pkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20Server%2011%20SP4-LTSSpkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20Server%2012%20SP2-BCLpkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20Server%2012%20SP3-BCLpkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20Server%2012%20SP3-LTSSpkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20Server%2012%20SP4-LTSSpkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20Server%2012%20SP5pkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20Server%2015%20SP1-BCLpkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20Server%2015%20SP1-LTSSpkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20Server%2015-LTSSpkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20Server%20for%20SAP%20Applications%2012%20SP3pkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20Server%20for%20SAP%20Applications%2012%20SP4pkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20Server%20for%20SAP%20Applications%2012%20SP5pkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20Server%20for%20SAP%20Applications%2015pkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20Server%20for%20SAP%20Applications%2015%20SP1pkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20Workstation%20Extension%2015%20SP2pkg:rpm/suse/strongswan&distro=SUSE%20Linux%20Enterprise%20Workstation%20Extension%2015%20SP3pkg:rpm/suse/strongswan&distro=SUSE%20OpenStack%20Cloud%208pkg:rpm/suse/strongswan&distro=SUSE%20OpenStack%20Cloud%209pkg:rpm/suse/strongswan&distro=SUSE%20OpenStack%20Cloud%20Crowbar%208pkg:rpm/suse/strongswan&distro=SUSE%20OpenStack%20Cloud%20Crowbar%209
< 5.8.2-lp152.2.18.1+ 33 more
- (no CPE)range: < 5.8.2-lp152.2.18.1
- (no CPE)range: < 5.8.2-11.21.1
- (no CPE)range: < 5.9.4-1.1
- (no CPE)range: < 5.1.3-26.16.1
- (no CPE)range: < 5.8.2-4.14.2
- (no CPE)range: < 5.8.2-4.14.2
- (no CPE)range: < 5.8.2-4.14.2
- (no CPE)range: < 5.8.2-4.14.2
- (no CPE)range: < 5.8.2-4.14.2
- (no CPE)range: < 5.8.2-11.21.1
- (no CPE)range: < 5.8.2-11.21.1
- (no CPE)range: < 5.8.2-11.21.1
- (no CPE)range: < 5.8.2-11.21.1
- (no CPE)range: < 4.4.0-6.36.9.1
- (no CPE)range: < 4.4.0-6.36.9.1
- (no CPE)range: < 5.1.3-26.16.1
- (no CPE)range: < 5.1.3-26.16.1
- (no CPE)range: < 5.1.3-26.16.1
- (no CPE)range: < 5.1.3-26.16.1
- (no CPE)range: < 5.1.3-26.16.1
- (no CPE)range: < 5.8.2-4.14.2
- (no CPE)range: < 5.8.2-4.14.2
- (no CPE)range: < 5.8.2-4.14.2
- (no CPE)range: < 5.1.3-26.16.1
- (no CPE)range: < 5.1.3-26.16.1
- (no CPE)range: < 5.1.3-26.16.1
- (no CPE)range: < 5.8.2-4.14.2
- (no CPE)range: < 5.8.2-4.14.2
- (no CPE)range: < 5.8.2-11.21.1
- (no CPE)range: < 5.8.2-11.21.1
- (no CPE)range: < 5.1.3-26.16.1
- (no CPE)range: < 5.1.3-26.16.1
- (no CPE)range: < 5.1.3-26.16.1
- (no CPE)range: < 5.1.3-26.16.1
Patches
Vulnerability mechanics
References
8- cert-portal.siemens.com/productcert/pdf/ssa-539476.pdfnvdPatchThird Party Advisory
- github.com/strongswan/strongswan/releases/tag/5.9.4nvdThird Party Advisory
- lists.debian.org/debian-lts-announce/2021/10/msg00014.htmlnvdMailing ListThird Party Advisory
- www.debian.org/security/2021/dsa-4989nvdThird Party Advisory
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5FJSATD2R2XHTG4P63GCMQ2N7EWKMME5/nvd
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WQSQ3BEC22NF4NCDZVCT4P3Q2ZIAJXGJ/nvd
- lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Y3TQ32JLJOBJDB2EJKSX2PBPB5NFG2D4/nvd
- www.strongswan.org/blog/2021/10/18/strongswan-vulnerability-%28cve-2021-41991%29.htmlnvd
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