CVE catalog
CVE-2020-28935
nsd: CVE-2020-28935
- Severity
- Medium · CVSS 4.4
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:N - Published
- Source
- [NVD] · [CVE record]
- EPSS
- 0.49% · Oct 25, 2026
NLnet Labs Unbound, up to and including version 1.12.0, and NLnet Labs NSD, up to and including version 4.3.3, contain a local vulnerability that would allow for a local symlink attack. When writing the PID file, Unbound and NSD create the file if it is not there, or open an existing file for writing. In case the file was already present, they would follow symlinks if the file happened to be a symlink instead of a regular file. An additional chown of the file would then take place after it was written, making the user Unbound/NSD is supposed to run as the new owner of the file. If an attacker has local access to the user Unbound/NSD runs as, she could create a symlink in place of the PID file pointing to a file that she would like to erase. If then Unbound/NSD is killed and the PID file is not cleared, upon restarting with root privileges, Unbound/NSD will rewrite any file pointed at by the symlink. This is a local vulnerability that could create a Denial of Service of the system Unbound/NSD is running on. It requires an attacker having access to the limited permission user Unbound/NSD runs as and point through the symlink to a critical file on the system.
Vulnerable and fixed packages
Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.
| Distribution | Package | Release | Version | Status |
|---|---|---|---|---|
| Debian | nsd | sid | 4.15.4-1 | fixed |
| Debian | nsd | forky | 4.15.4-1 | fixed |
| Debian | nsd | trixie | 4.12.0-1 | fixed |
| Debian | nsd | bookworm | 4.6.1-1 | fixed |
| Debian | unbound | sid | 1.26.2-1 | fixed |
| Debian | unbound | forky | 1.26.2-1 | fixed |
| Debian | unbound | trixie | 1.22.0-2+deb13u3 | fixed |
| Debian | unbound | trixie-security | 1.26.2-0+deb13u1 | fixed |
| Debian | unbound | bookworm | 1.17.1-2+deb12u4 | fixed |
| Debian | unbound | bookworm-security | 1.17.1-2+deb12u3 | fixed |
| Ubuntu | unbound | pro | 1.4.22-1ubuntu6 | vulnerable |
| Ubuntu | unbound | pro | 1.5.7-1ubuntu1 | vulnerable |
| Ubuntu | unbound | pro | 1.5.7-1ubuntu2 | vulnerable |
| Ubuntu | unbound | pro | 1.5.8-1ubuntu1 | vulnerable |
| Ubuntu | unbound | pro | 1.5.8-1ubuntu1.1 | vulnerable |
| Ubuntu | unbound | pro | 1.5.8-1ubuntu1.1+esm1 | vulnerable |
| Ubuntu | unbound | pro | 1.5.8-1ubuntu1.1+esm2 | vulnerable |
| Ubuntu | unbound | pro | 1.5.8-1ubuntu1.1+esm3 | vulnerable |
| Ubuntu | unbound | pro | 1.5.8-1ubuntu1.1+esm4 | vulnerable |
| Ubuntu | unbound | pro | 1.5.8-1ubuntu1.1+esm5 | vulnerable |
| Ubuntu | unbound | 18.04 | 1.6.5-1 | vulnerable |
| Ubuntu | unbound | 18.04 | 1.6.7-1 | vulnerable |
| Ubuntu | unbound | 18.04 | 1.6.7-1build1 | vulnerable |
| Ubuntu | unbound | 18.04 | 1.6.7-1ubuntu1 | vulnerable |
| Ubuntu | unbound | 18.04 | 1.6.7-1ubuntu2 | vulnerable |
| Ubuntu | unbound | 18.04 | 1.6.7-1ubuntu2.1 | vulnerable |
| Ubuntu | unbound | 18.04 | 1.6.7-1ubuntu2.2 | vulnerable |
| Ubuntu | unbound | 18.04 | 1.6.7-1ubuntu2.3 | vulnerable |
| Ubuntu | unbound | 18.04 | 1.6.7-1ubuntu2.4 | fixed |
| Ubuntu | unbound | 20.04 | 1.9.0-2ubuntu1 | vulnerable |
| Ubuntu | unbound | 20.04 | 1.9.0-2ubuntu2 | vulnerable |
| Ubuntu | unbound | 20.04 | 1.9.4-2 | vulnerable |
| Ubuntu | unbound | 20.04 | 1.9.4-2ubuntu1 | vulnerable |
| Ubuntu | unbound | 20.04 | 1.9.4-2ubuntu1.1 | vulnerable |
| Ubuntu | unbound | 20.04 | 1.9.4-2ubuntu1.2 | fixed |
| Alpine | nsd | 3.12 | 4.3.4-r0 | fixed |
| Alpine | nsd | 3.13 | 4.3.4-r0 | fixed |
| Alpine | nsd | 3.14 | 4.3.4-r0 | fixed |
| Alpine | nsd | 3.15 | 4.3.4-r0 | fixed |
| Alpine | nsd | 3.16 | 4.3.4-r0 | fixed |
| Alpine | nsd | 3.17 | 4.3.4-r0 | fixed |
| Alpine | nsd | 3.18 | 4.3.4-r0 | fixed |
| Alpine | nsd | 3.19 | 4.3.4-r0 | fixed |
| Alpine | nsd | 3.20 | 4.3.4-r0 | fixed |
| Alpine | nsd | 3.21 | 4.3.4-r0 | fixed |
| Alpine | nsd | 3.22 | 4.3.4-r0 | fixed |
| Alpine | nsd | 3.23 | 4.3.4-r0 | fixed |
| Alpine | nsd | 3.24 | 4.3.4-r0 | fixed |
| Opensuse | sslh | tumbleweed | 2.2.3-1.1 | fixed |
Fixed-version evidence
| Distribution | Package | Type | Release | Fixed version | Urgency | Origin | Bugs |
|---|---|---|---|---|---|---|---|
| Debian | nsd | source | sid | 4.3.4-1 | not yet assigned | Not reported | Not reported |
| Debian | nsd | source | forky | 4.3.4-1 | not yet assigned | Not reported | Not reported |
| Debian | nsd | source | trixie | 4.3.4-1 | not yet assigned | Not reported | Not reported |
| Debian | nsd | source | bookworm | 4.3.4-1 | not yet assigned | Not reported | Not reported |
| Debian | unbound | source | sid | 1.13.0-1 | not yet assigned | Not reported | [977165] |
| Debian | unbound | source | forky | 1.13.0-1 | not yet assigned | Not reported | [977165] |
| Debian | unbound | source | trixie | 1.13.0-1 | not yet assigned | Not reported | [977165] |
| Debian | unbound | source | bookworm | 1.13.0-1 | not yet assigned | Not reported | [977165] |
| Ubuntu | unbound | deb | 18.04 | 1.6.7-1ubuntu2.4 | Not reported | UBUNTU-CVE-2020-28935 | Not reported |
| Ubuntu | unbound | deb | 20.04 | 1.9.4-2ubuntu1.2 | Not reported | UBUNTU-CVE-2020-28935 | Not reported |
| Alpine | nsd | apk | 3.12 | 4.3.4-r0 | Not reported | ALPINE-CVE-2020-28935 | Not reported |
| Alpine | nsd | apk | 3.13 | 4.3.4-r0 | Not reported | ALPINE-CVE-2020-28935 | Not reported |
| Alpine | nsd | apk | 3.14 | 4.3.4-r0 | Not reported | ALPINE-CVE-2020-28935 | Not reported |
| Alpine | nsd | apk | 3.15 | 4.3.4-r0 | Not reported | ALPINE-CVE-2020-28935 | Not reported |
| Alpine | nsd | apk | 3.16 | 4.3.4-r0 | Not reported | ALPINE-CVE-2020-28935 | Not reported |
| Alpine | nsd | apk | 3.17 | 4.3.4-r0 | Not reported | ALPINE-CVE-2020-28935 | Not reported |
| Alpine | nsd | apk | 3.18 | 4.3.4-r0 | Not reported | ALPINE-CVE-2020-28935 | Not reported |
| Alpine | nsd | apk | 3.19 | 4.3.4-r0 | Not reported | ALPINE-CVE-2020-28935 | Not reported |
| Alpine | nsd | apk | 3.20 | 4.3.4-r0 | Not reported | ALPINE-CVE-2020-28935 | Not reported |
| Alpine | nsd | apk | 3.21 | 4.3.4-r0 | Not reported | ALPINE-CVE-2020-28935 | Not reported |
| Alpine | nsd | apk | 3.22 | 4.3.4-r0 | Not reported | ALPINE-CVE-2020-28935 | Not reported |
| Alpine | nsd | apk | 3.23 | 4.3.4-r0 | Not reported | ALPINE-CVE-2020-28935 | Not reported |
| Alpine | nsd | apk | 3.24 | 4.3.4-r0 | Not reported | ALPINE-CVE-2020-28935 | Not reported |
| Opensuse | sslh | rpm | tumbleweed | 2.2.3-1.1 | Not reported | OPENSUSE-SU-2025:15069-1 | Not reported |
OpenFactory catalog packages
Matching against OpenFactory catalog package versions is in progress.
[Debian 12 (Bookworm)]
- [libunbound8]Unknown
Source package: [unbound]
Details (4)
1.17.1-2+deb12u4· amd64 · bookwormFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
1.17.1-2+deb12u4· arm64 · bookwormFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
1.17.1-2+deb12u3· amd64 · bookworm-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
1.17.1-2+deb12u3· arm64 · bookworm-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- [libunbound-dev]Unknown
Source package: [unbound]
Details (4)
1.17.1-2+deb12u4· amd64 · bookwormFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
1.17.1-2+deb12u4· arm64 · bookwormFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
1.17.1-2+deb12u3· amd64 · bookworm-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
1.17.1-2+deb12u3· arm64 · bookworm-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- [nsd]Unknown
Details (2)
4.6.1-1· amd64 · bookwormFixed · Fixed:
4.3.4-1dsa · nsd · debian · bookworm; dsa · nsd · debian · 12
4.6.1-1· arm64 · bookwormFixed · Fixed:
4.3.4-1dsa · nsd · debian · bookworm; dsa · nsd · debian · 12
- [python3-unbound]Unknown
Source package: [unbound]
Details (4)
1.17.1-2+deb12u4· amd64 · bookwormFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
1.17.1-2+deb12u4· arm64 · bookwormFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
1.17.1-2+deb12u3· amd64 · bookworm-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
1.17.1-2+deb12u3· arm64 · bookworm-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- [unbound]Unknown
Details (4)
1.17.1-2+deb12u4· amd64 · bookwormFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
1.17.1-2+deb12u4· arm64 · bookwormFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
1.17.1-2+deb12u3· amd64 · bookworm-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
1.17.1-2+deb12u3· arm64 · bookworm-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- [unbound-anchor]Unknown
Source package: [unbound]
Details (4)
1.17.1-2+deb12u4· amd64 · bookwormFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
1.17.1-2+deb12u4· arm64 · bookwormFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
1.17.1-2+deb12u3· amd64 · bookworm-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
1.17.1-2+deb12u3· arm64 · bookworm-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
- [unbound-host]Unknown
Source package: [unbound]
Details (4)
1.17.1-2+deb12u4· amd64 · bookwormFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
1.17.1-2+deb12u4· arm64 · bookwormFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
1.17.1-2+deb12u3· amd64 · bookworm-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
1.17.1-2+deb12u3· arm64 · bookworm-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · bookworm; dsa · unbound · debian · 12
[Debian 13 (Trixie)]
- [libunbound8]Unknown
Source package: [unbound]
Details (6)
1.22.0-2+deb13u3· amd64 · trixieFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.22.0-2+deb13u3· arm64 · trixieFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.22.0-2+deb13u3· amd64 · trixie-security · Historical versionFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.22.0-2+deb13u3· arm64 · trixie-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.26.1-0+deb13u1· amd64 · trixie-security · Historical versionFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.26.2-0+deb13u1· amd64 · trixie-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
- [libunbound-dev]Unknown
Source package: [unbound]
Details (6)
1.22.0-2+deb13u3· amd64 · trixieFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.22.0-2+deb13u3· arm64 · trixieFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.22.0-2+deb13u3· amd64 · trixie-security · Historical versionFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.22.0-2+deb13u3· arm64 · trixie-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.26.1-0+deb13u1· amd64 · trixie-security · Historical versionFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.26.2-0+deb13u1· amd64 · trixie-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
- [nsd]Unknown
Details (2)
4.12.0-1· amd64 · trixieFixed · Fixed:
4.3.4-1dsa · nsd · debian · 13
4.12.0-1· arm64 · trixieFixed · Fixed:
4.3.4-1dsa · nsd · debian · 13
- [python3-unbound]Unknown
Source package: [unbound]
Details (6)
1.22.0-2+deb13u3· amd64 · trixieFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.22.0-2+deb13u3· arm64 · trixieFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.22.0-2+deb13u3· amd64 · trixie-security · Historical versionFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.22.0-2+deb13u3· arm64 · trixie-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.26.1-0+deb13u1· amd64 · trixie-security · Historical versionFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.26.2-0+deb13u1· amd64 · trixie-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
- [unbound]Unknown
Details (6)
1.22.0-2+deb13u3· amd64 · trixieFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.22.0-2+deb13u3· arm64 · trixieFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.22.0-2+deb13u3· amd64 · trixie-security · Historical versionFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.22.0-2+deb13u3· arm64 · trixie-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.26.1-0+deb13u1· amd64 · trixie-security · Historical versionFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.26.2-0+deb13u1· amd64 · trixie-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
- [unbound-anchor]Unknown
Source package: [unbound]
Details (6)
1.22.0-2+deb13u3· amd64 · trixieFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.22.0-2+deb13u3· arm64 · trixieFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.22.0-2+deb13u3· amd64 · trixie-security · Historical versionFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.22.0-2+deb13u3· arm64 · trixie-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.26.1-0+deb13u1· amd64 · trixie-security · Historical versionFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.26.2-0+deb13u1· amd64 · trixie-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
- [unbound-host]Unknown
Source package: [unbound]
Details (6)
1.22.0-2+deb13u3· amd64 · trixieFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.22.0-2+deb13u3· arm64 · trixieFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.22.0-2+deb13u3· amd64 · trixie-security · Historical versionFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.22.0-2+deb13u3· arm64 · trixie-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.26.1-0+deb13u1· amd64 · trixie-security · Historical versionFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
1.26.2-0+deb13u1· amd64 · trixie-securityFixed · Fixed:
1.13.0-1dsa · unbound · debian · 13
[openSUSE Tumbleweed]
Observed:
References
- [https://access.redhat.com/errata/RHSA-2021:1853]
- [https://ftp.suse.com/pub/projects/security/csaf/rhsa-2021_1853.json]
- [https://osv.dev/vulnerability/ALPINE-CVE-2020-28935]
- [https://osv.dev/vulnerability/DEBIAN-CVE-2020-28935]
- [https://osv.dev/vulnerability/DLA-3371-1]
- [https://osv.dev/vulnerability/UBUNTU-CVE-2020-28935]
- [https://osv.dev/vulnerability/openSUSE-SU-2025:15069-1]
- [https://security-tracker.debian.org/tracker/CVE-2020-28935]
[Debian Security Tracker] · [FIRST EPSS] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]