# CVE-2021-25219: Lame cache can be abused to severely degrade resolver performance > Attackers can degrade BIND resolver performance by exploiting a flaw in lame cache data structures, causing significant delays in client query processing. - **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 27 Oct 2021 - **Updated:** 16 Sep 2024 - **Also known as:** ALPINE-CVE-2021-25219, ALSA-2022:2092, AZL-6327, CLSA-2021-1635957830, CLSA-2021-1637070791, CLSA-2021-1639681836, CLSA-2022-1654175851, CLSA-2022-1654511849, DEBIAN-CVE-2021-25219, DSA-4994-1, GHSA-x6vq-rxvf-3ggc, MGASA-2021-0560, OESA-2021-1459, RHSA-2022:2092, RLSA-2022:2092, SUSE-SU-2021:3657-1, SUSE-SU-2021:3773-1, SUSE-SU-2022:0151-1, UBUNTU-CVE-2021-25219, USN-5126-1, USN-5126-2, openSUSE-SU-2021:1502-1, openSUSE-SU-2021:3773-1, openSUSE-SU-2022:0151-1, openSUSE-SU-2024:11660-1 ## What is CVE-2021-25219? CVE-2021-25219 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 27 Oct 2021. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description In BIND 9.3.0 -> 9.11.35, 9.12.0 -> 9.16.21, and versions 9.9.3-S1 -> 9.11.35-S1 and 9.16.8-S1 -> 9.16.21-S1 of BIND Supported Preview Edition, as well as release versions 9.17.0 -> 9.17.18 of the BIND 9.17 development branch, exploitation of broken authoritative servers using a flaw in response processing can cause degradation in BIND resolver performance. The way the lame cache is currently designed makes it possible for its internal data structures to grow almost infinitely, which may cause significant delays in client query processing. ## Which versions are affected by CVE-2021-25219? It affects 15 products. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `bind` | AlmaLinux:8 | All versions | 32:9.11.36-3.el8 | | `bind-chroot` | AlmaLinux:8 | All versions | 32:9.11.36-3.el8 | | `bind-devel` | AlmaLinux:8 | All versions | 32:9.11.36-3.el8 | | `bind-export-devel` | AlmaLinux:8 | All versions | 32:9.11.36-3.el8 | | `bind-export-libs` | AlmaLinux:8 | All versions | 32:9.11.36-3.el8 | | `bind-libs` | AlmaLinux:8 | All versions | 32:9.11.36-3.el8 | | `bind-libs-lite` | AlmaLinux:8 | All versions | 32:9.11.36-3.el8 | | `bind-license` | AlmaLinux:8 | All versions | 32:9.11.36-3.el8 | | `bind-lite-devel` | AlmaLinux:8 | All versions | 32:9.11.36-3.el8 | | `bind-pkcs11` | AlmaLinux:8 | All versions | 32:9.11.36-3.el8 | | `bind-pkcs11-devel` | AlmaLinux:8 | All versions | 32:9.11.36-3.el8 | | `bind-pkcs11-libs` | AlmaLinux:8 | All versions | 32:9.11.36-3.el8 | | `bind-pkcs11-utils` | AlmaLinux:8 | All versions | 32:9.11.36-3.el8 | | `bind-sdb` | AlmaLinux:8 | All versions | 32:9.11.36-3.el8 | | `bind-sdb-chroot` | AlmaLinux:8 | All versions | 32:9.11.36-3.el8 | | `bind-utils` | AlmaLinux:8 | All versions | 32:9.11.36-3.el8 | | `python3-bind` | AlmaLinux:8 | All versions | 32:9.11.36-3.el8 | | `bind` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-chroot` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-debugsource` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-devel` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-export-libs-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-libs` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-libs-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-libs-lite` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-libs-lite-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-license` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-lite-devel` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-pkcs11` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-pkcs11-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-pkcs11-devel` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-pkcs11-libs` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-pkcs11-libs-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-pkcs11-utils` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-pkcs11-utils-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-sdb` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-sdb-chroot` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-sdb-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | | `bind-utils` | Red Hat:enterprise_linux:8::appstream | All versions | 32:9.11.36-3.el8 | Products: Debian Debian Linux, Fedoraproject Fedora, Isc Bind, Netapp Cloud Backup, Netapp H300e Firmware, Netapp H300s Firmware, Netapp H410c Firmware, Netapp H410s Firmware, Netapp H500e Firmware, Netapp H500s Firmware, Netapp H700e Firmware, Netapp H700s Firmware, Oracle Http Server, Oracle Zfs Storage Appliance Kit, Siemens Sinec Infrastructure Network Services. ## How do I fix CVE-2021-25219? Upgrade to a fixed version. ## Is CVE-2021-25219 being exploited? There is no known exploitation of CVE-2021-25219 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-2021-25219 and fix it if it is affected. What it is: CVE-2021-25219 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 27 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-2021-25219 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-2021-25219/ (Markdown: https://insights.sbomify.com/CVE-2021-25219/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2021-25219 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-25219 - OSV: https://osv.dev/vulnerability/CVE-2021-25219 --- From sbomify Insights: https://insights.sbomify.com/CVE-2021-25219/ Summaries are generated and may contain mistakes; the official description above is the record.