CVE-2026-101337
Stack overwrite from specially formatted base64 RDATA field
CVE-2026-101337 is a high vulnerability (CVSS 8.7) in Nlnet Labs Nsd, published October 14, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.34%, the 27th percentile. Fixed in nsd 4.11.1-r1.
When base64 data is split up in pieces, of 3 character or less, tokens were incorrectly calculated to produce 0 bytes. This enables attackers to overwrite the stack with up to 64K of attacker controlled data. Zone files which are written out by NSD itself, such as for zones for which the NSD instance is secondary, will not be formatted like this. The zone file must be fed to NSD directly, (but it could come, for example, from an operator controlled provisioning system).
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
8.7
Stack overwrite from specially formatted base64 RDATA field
When base64 data is split up in pieces, of 3 character or less, tokens were incorrectly calculated to produce 0 bytes. This enables attackers to overwrite the stack with up to 64K of attacker controlled data. Zone files which are written out by NSD itself, such as for zones for which the NSD instance is secondary, will not be formatted like this. The zone file must be fed to NSD directly, (but it could come, for example, from an operator controlled provisioning system).
- Record
CVE-2026-101337- CVSS 4.0
- 8.7 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - Weakness
- CWE-121
- Updated
- 2026-11-02
EUVDEUVD-2026-100982
8.7
When base64 data is split up in pieces, of 3 character or less, tokens were incorrectly calculated to produce 0 bytes. This enables attackers to overwrite the stack with up to 64K of attacker controlled data. Zone files which are written out by NSD itself, such as for zones for which the NSD instance is secondary, will not be formatted like this. The zone file must be fed to NSD directly, (but it could come, for example, from an operator controlled provisioning system).
- Record
EUVD-2026-100982- CVSS 4.0
- 8.7 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-w2rq-89vw-p64m
8.7
When base64 data is split up in pieces, of 3 character or less, tokens were incorrectly...
When base64 data is split up in pieces, of 3 character or less, tokens were incorrectly calculated to produce 0 bytes. This enables attackers to overwrite the stack with up to 64K of attacker controlled data. Zone files which are written out by NSD itself, such as for zones for which the NSD instance is secondary, will not be formatted like this. The zone file must be fed to NSD directly, (but it could come, for example, from an operator controlled provisioning system).
- Record
GHSA-w2rq-89vw-p64m- CVSS 4.0
- 8.7 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - Weakness
- CWE-121
- Updated
- 2026-11-02
NVD
8.7
When base64 data is split up in pieces, of 3 character or less, tokens were incorrectly calculated to produce 0 bytes. This enables attackers to overwrite the stack with up to 64K of attacker controlled data. Zone files which are written out by NSD itself, such as for zones for which the NSD instance is secondary, will not be formatted like this. The zone file must be fed to NSD directly, (but it could come, for example, from an operator controlled provisioning system).
- Record
CVE-2026-101337- CVSS 4.0
- 8.7 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - Weakness
- CWE-121
- Updated
- 2026-11-02
OSVALPINE-CVE-2026-101337
8.7
When base64 data is split up in pieces, of 3 character or less, tokens were incorrectly calculated to produce 0 bytes. This enables attackers to overwrite the stack with up to 64K of attacker controlled data. Zone files which are written out by NSD itself, such as for zones for which the NSD instance is secondary, will not be formatted like this. The zone file must be fed to NSD directly, (but it could come, for example, from an operator controlled provisioning system).
- Record
ALPINE-CVE-2026-101337- CVSS 4.0
- 8.7 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - Updated
- 2026-11-03
OSVDEBIAN-CVE-2026-101337
8.7
When base64 data is split up in pieces, of 3 character or less, tokens were incorrectly calculated to produce 0 bytes. This enables attackers to overwrite the stack with up to 64K of attacker controlled data. Zone files which are written out by NSD itself, such as for zones for which the NSD instance is secondary, will not be formatted like this. The zone file must be fed to NSD directly, (but it could come, for example, from an operator controlled provisioning system).
- Record
DEBIAN-CVE-2026-101337- CVSS 4.0
- 8.7 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-101337
8.7
When base64 data is split up in pieces, of 3 character or less, tokens were incorrectly calculated to produce 0 bytes. This enables attackers to overwrite the stack with up to 64K of attacker controlled data. Zone files which are written out by NSD itself, such as for zones for which the NSD instance is secondary, will not be formatted like this. The zone file must be fed to NSD directly, (but it could come, for example, from an operator controlled provisioning system).
- Record
UBUNTU-CVE-2026-101337- CVSS 4.0
- 8.7 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
nsdAlpine:v3.21 |
before 4.11.1-r1 | 4.11.1-r1 |
nsdAlpine:v3.22 |
before 4.12.0-r1 | 4.12.0-r1 |
nsdAlpine:v3.23 |
before 4.13.0-r1 | 4.13.0-r1 |
nsdAlpine:v3.24 |
before 4.14.3-r1 | 4.14.3-r1 |
nsdDebian:12 |
All versions, plus listed versions 4.10.1-14.10.1~rc2-14.10.1~rc2-24.11.0-14.11.1-1 Show 22 moreShow less4.12.0-14.12.0-24.13.0-14.13.0-24.13.0-34.13.0-44.13.0-54.13.0-64.14.0-14.14.1-14.14.2-14.14.3-14.15.0-14.15.0~rc1-14.15.1-14.15.2-14.15.3-14.15.4-14.6.1-14.7.0-14.8.0-14.9.1-1 |
None known |
nsdDebian:13 |
All versions, plus listed versions 4.12.0-14.12.0-24.13.0-14.13.0-24.13.0-3 Show 13 moreShow less4.13.0-44.13.0-54.13.0-64.14.0-14.14.1-14.14.2-14.14.3-14.15.0-14.15.0~rc1-14.15.1-14.15.2-14.15.3-14.15.4-1 |
None known |
nsdDebian:14 |
before 4.15.3-1, plus listed versions 4.12.0-14.12.0-24.13.0-14.13.0-24.13.0-3 Show 11 moreShow less4.13.0-44.13.0-54.13.0-64.14.0-14.14.1-14.14.2-14.14.3-14.15.0-14.15.0~rc1-14.15.1-14.15.2-1 |
4.15.3-1 |
nsdUbuntu:Pro:16.04:LTS |
All versions, plus listed versions 4.1.2-14.1.6-14.1.7-14.1.7-1ubuntu0.1~esm1 |
None known |
nsdUbuntu:Pro:18.04:LTS |
All versions, plus listed versions 4.1.16-1build14.1.17-14.1.17-1build14.1.17-1ubuntu0.1~esm1 |
None known |
nsdUbuntu:Pro:20.04:LTS |
All versions, plus listed versions 4.1.26-14.1.26-1build14.1.26-1ubuntu0.1~esm1 |
None known |
Show 4 moreShow less
| Package | Affected | Fixed |
|---|---|---|
nsdUbuntu:Pro:22.04:LTS |
All versions, plus listed versions 4.3.5-14.3.7-14.3.8-14.3.8-1build14.3.9-14.3.9-1ubuntu0.1~esm1 |
None known |
nsdUbuntu:Pro:24.04:LTS |
All versions, plus listed versions 4.7.0-14.8.0-14.8.0-1build14.8.0-1build34.8.0-1ubuntu0.1~esm1 |
None known |
nsdUbuntu:26.10 |
All versions, plus listed versions 4.14.0-14.14.2-14.14.3-14.15.0-14.15.0-1build1 |
None known |
nsdUbuntu:Pro:26.04:LTS |
All versions, plus listed versions 4.12.0-14.13.0-64.14.0-14.14.0-1ubuntu0.1~esm1 |
None known |
History
| When | Changed | Sources |
|---|---|---|
| 2026-11-03 | affected | OSV |
| 2026-11-02 | created | CVE List, EUVD, GitHub Advisories, NVD, OSV |
References
nlnetlabs.nl/downloads/nsd/CVE-2026-101337.txt
nvd.nist.gov/vuln/detail/CVE-2026-101337
github.com/advisories/GHSA-w2rq-89vw-p64m
security.alpinelinux.org/vuln/CVE-2026-101337
security-tracker.debian.org/tracker/CVE-2026-101337
ubuntu.com/security/CVE-2026-101337
cve.org/CVERecord?id=CVE-2026-101337
openwall.com/lists/oss-security/2026/10/14/12