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CVE-2021-41990· NVD / CVE Program· CNA mitre

The gmp plugin in strongSwan before 5.9.4 has a remote integer overflow via a crafted certificate with an RSASSA-PSS signature.

Noroxi assessment

Priority: Monitor (action score 32/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 6.7% (FIRST EPSS); higher than 93.8% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: strongswan (Alpine:v3.12) 5.8.4-r3; strongswan (Alpine:v3.13) 5.9.1-r1; strongswan (Alpine:v3.14) 5.9.1-r2.

Low priority for now. Upgrade to strongswan (Alpine:v3.12) 5.8.4-r3; strongswan (Alpine:v3.13) 5.9.1-r1; strongswan (Alpine:v3.14) 5.9.1-r2 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

The gmp plugin in strongSwan before 5.9.4 has a remote integer overflow via a crafted certificate with an RSASSA-PSS signature. For example, this can be triggered by an unrelated self-signed CA certificate sent by an initiator. Remote code execution cannot occur.

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Oct 18, 2021
Updated
Jun 17, 2026
EPSS
6.7% · 93th percentile

Report tools

JSON

Action score

32

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
2 / 30 · 6.7%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
strongswanstrongswan
debiandebian linux
fedoraprojectfedora
siemens6gk6108-4am00-2ba2 firmware
siemens6gk6108-4am00-2ba2
siemens6gk6108-4am00-2da2 firmware
siemens6gk6108-4am00-2da2
siemens6gk5804-0ap00-2aa2 firmware
siemens6gk5804-0ap00-2aa2
siemens6gk5812-1aa00-2aa2 firmware
siemens6gk5812-1aa00-2aa2
siemens6gk5812-1ba00-2aa2 firmware

and 25 more

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • debian debian linux10.0
  • debian debian linux11.0
  • fedoraproject fedora33
  • fedoraproject fedora34
  • fedoraproject fedora35
  • siemens 6gk5615-0aa00-2aa2 firmwareall versions
  • siemens 6gk5804-0ap00-2aa2 firmwareall versions
  • siemens 6gk5812-1aa00-2aa2 firmwareall versions
  • siemens 6gk5812-1ba00-2aa2 firmwareall versions
  • siemens 6gk5816-1aa00-2aa2 firmwareall versions
  • siemens 6gk5816-1ba00-2aa2 firmwareall versions
  • siemens 6gk5826-2ab00-2ab2 firmwareall versions
  • siemens 6gk5856-2ea00-3aa1 firmwareall versions
  • siemens 6gk5856-2ea00-3da1 firmwareall versions
  • siemens 6gk5874-2aa00-2aa2 firmwareall versions
  • siemens 6gk5874-3aa00-2aa2 firmwareall versions
  • siemens 6gk5876-3aa02-2ba2 firmwareall versions
  • siemens 6gk5876-3aa02-2ea2 firmwareall versions
  • siemens 6gk5876-4aa00-2ba2 firmwareall versions
  • siemens 6gk5876-4aa00-2da2 firmwareall versions

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Alpine:v3.12strongswanfrom 5.6.1 · before 5.8.4-r35.8.4-r3
Alpine:v3.13strongswanfrom 5.6.1 · before 5.9.1-r15.9.1-r1
Alpine:v3.14strongswanfrom 5.6.1 · before 5.9.1-r25.9.1-r2
Alpine:v3.15strongswanfrom 5.6.1 · before 5.9.1-r35.9.1-r3
Debian:10strongswanbefore 5.7.2-1+deb10u15.7.2-1+deb10u1
Debian:11strongswanbefore 5.9.1-1+deb11u15.9.1-1+deb11u1
Debian:12strongswanbefore 5.9.4-15.9.4-1
openSUSE:Leap 15.2strongswanbefore 5.8.2-lp152.2.18.15.8.2-lp152.2.18.1
openSUSE:Leap 15.3strongswanbefore 5.8.2-11.21.15.8.2-11.21.1
openSUSE:Tumbleweedstrongswanbefore 5.9.4-1.15.9.4-1.1
SUSE:Linux Enterprise High Performance Computing 15-ESPOSstrongswanbefore 5.8.2-4.14.25.8.2-4.14.2
SUSE:Linux Enterprise Module for Basesystem 15 SP2strongswanbefore 5.8.2-11.21.15.8.2-11.21.1

Same product

strongswan: all records

Other highest-scoring records for the same primary product.

  • CVE-2023-41913strongSwan before 5.9.12 has a buffer overflow and possible unauthenticated remote code execution via a DH public value that exceeds the int
    40Plan
  • CVE-2023-26463strongSwan 5.9.8 and 5.9.9 potentially allows remote code execution because it uses a variable named "public" for two different purposes wit
    40Plan
  • CVE-2015-3991strongSwan 5.2.2 and 5.3.0 allows remote attackers to cause a denial of service (daemon crash) or execute arbitrary code.
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2018-16152Sep 26, 2018 · In verify_emsa_pkcs1_signature() in gmp_rsa_public_key.c in the gmp plugin in strongSwan 4.x and 5.x before 5.7.0, the RSA implementation ba
    31Monitor
  • ← EarlierCVE-2018-17540Oct 3, 2018 · The gmp plugin in strongSwan before 5.7.1 has a Buffer Overflow via a crafted certificate.
    31Monitor
  • Later →CVE-2021-41991Oct 18, 2021 · The in-memory certificate cache in strongSwan before 5.9.4 has a remote integer overflow upon receiving many requests with different certifi
    32Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
alpine:strongswan5.8.4-r3 · Alpine:v3.12Package registry (OSV)
debian:strongswan5.9.4-1 · Debian:12Package registry (OSV)
opensuse:strongswan5.8.2-lp152.2.18.1 · openSUSE:Leap 15.2Package registry (OSV)
suse:strongswan5.8.2-11.21.1 · SUSE:Linux Enterprise Module for Basesystem 15 SP2Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-190 · Integer Overflow or Wraparound

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (6 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records