# CVE-2021-41991: Integer overflow in n/a > Remote attackers can trigger an integer overflow in strongSwan's certificate cache, potentially leading to remote code execution or denial of service. - **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 18 Oct 2021 - **Updated:** 4 Aug 2024 - **Also known as:** ALPINE-CVE-2021-41991, AZL-6897, DEBIAN-CVE-2021-41991, DLA-2788-1, GHSA-jpr7-w98h-cvgm, SUSE-SU-2021:14827-1, SUSE-SU-2021:3468-1, UBUNTU-CVE-2021-41991, USN-5111-2 ## What is CVE-2021-41991? CVE-2021-41991 is a high-severity vulnerability in Debian Debian Linux, published on 18 Oct 2021. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official 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. Weakness: CWE-190 (Integer Overflow or Wraparound) ## Which versions are affected by CVE-2021-41991? It affects 25 products. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `strongswan` | SUSE:HPE Helion OpenStack 8 | All versions | 5.1.3-26.16.1 | | `strongswan` | SUSE:Linux Enterprise Point of Sale 11 SP3 | All versions | 4.4.0-6.36.9.1 | | `strongswan` | SUSE:Linux Enterprise Server 11 SP4-LTSS | All versions | 4.4.0-6.36.9.1 | | `strongswan` | SUSE:Linux Enterprise Server 12 SP2-BCL | All versions | 5.1.3-26.16.1 | | `strongswan` | SUSE:Linux Enterprise Server 12 SP3-BCL | All versions | 5.1.3-26.16.1 | | `strongswan` | SUSE:Linux Enterprise Server 12 SP3-LTSS | All versions | 5.1.3-26.16.1 | | `strongswan` | SUSE:Linux Enterprise Server 12 SP4-LTSS | All versions | 5.1.3-26.16.1 | | `strongswan` | SUSE:Linux Enterprise Server 12 SP5 | All versions | 5.1.3-26.16.1 | | `strongswan` | SUSE:Linux Enterprise Server for SAP Applications 12 SP3 | All versions | 5.1.3-26.16.1 | | `strongswan` | SUSE:Linux Enterprise Server for SAP Applications 12 SP4 | All versions | 5.1.3-26.16.1 | | `strongswan` | SUSE:Linux Enterprise Server for SAP Applications 12 SP5 | All versions | 5.1.3-26.16.1 | | `strongswan` | SUSE:OpenStack Cloud 8 | All versions | 5.1.3-26.16.1 | | `strongswan` | SUSE:OpenStack Cloud 9 | All versions | 5.1.3-26.16.1 | | `strongswan` | SUSE:OpenStack Cloud Crowbar 8 | All versions | 5.1.3-26.16.1 | | `strongswan` | SUSE:OpenStack Cloud Crowbar 9 | All versions | 5.1.3-26.16.1 | Products: Debian Debian Linux, Fedoraproject Fedora, Siemens Cp 1543-1 Firmware, Siemens Scalance Sc622-2c Firmware, Siemens Scalance Sc632-2c Firmware, Siemens Scalance Sc636-2c Firmware, Siemens Scalance Sc642-2c Firmware, Siemens Scalance Sc646-2c Firmware, Siemens Simatic Cp 1242-7 Gprs V2 Firmware, Siemens Simatic Cp 1243-1 Firmware, Siemens Simatic Cp 1243-7 Lte\/Us Firmware, Siemens Simatic Cp 1542sp-1 Firmware, Siemens Simatic Cp 1542sp-1 Irc Firmware, Siemens Simatic Cp 1543sp-1 Firmware, Siemens Simatic Net Cp1243-7 Lte Eu Firmware, Siemens Simatic Net Cp 1243-8 Irc Firmware, Siemens Simatic Net Cp 1545-1 Firmware, Siemens Sinema Remote Connect Server, Siemens Siplus Et 200sp Cp 1542sp-1 Irc Tx Rail Firmware, Siemens Siplus Et 200sp Cp 1543sp-1 Isec Firmware and 5 more. ## How do I fix CVE-2021-41991? Upgrade to a fixed version. ## Is CVE-2021-41991 being exploited? There is no known exploitation of CVE-2021-41991 in the wild and no public exploit code. ## Other vulnerabilities in Debian Debian Linux - [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild) - [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild) - [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild) - [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild) - [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2021-41991 and fix it if it is affected. What it is: CVE-2021-41991 is a high-severity vulnerability in Debian Debian Linux, published on 18 Oct 2021. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of CVE-2021-41991 in the wild and no public exploit code. Affected product: Debian Debian Linux. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2021-41991/ (Markdown: https://insights.sbomify.com/CVE-2021-41991/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2021-41991 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-41991 - OSV: https://osv.dev/vulnerability/CVE-2021-41991 --- From sbomify Insights: https://insights.sbomify.com/CVE-2021-41991/ Summaries are generated and may contain mistakes; the official description above is the record.