coredns: Predictable Seed in Pseudo-Random Number Generator (PRNG)
CVE-2026-26018 is a high-severity predictable seed in pseudo-random number generator (PRNG) vulnerability in coredns, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected coredns versions: < 1.14.2. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.24% chance of exploitation within 30 days, higher than 70% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of coredns you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Coredns | coredns | < 1.14.2 | Not stated |
| Red Hat | Red Hat Advanced Cluster Management for Kubernetes 2.13 | Not specified in the record | Not stated |
| Red Hat | Red Hat Advanced Cluster Management for Kubernetes 2.14 | Not specified in the record | Not stated |
| Red Hat | Red Hat Advanced Cluster Management for Kubernetes 2.15 | Not specified in the record | Not stated |
| Red Hat | Red Hat Connectivity Link 1 | Not specified in the record | Not stated |
| Red Hat | Red Hat OpenShift Container Platform 4 | Not specified in the record | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CNA (github.com).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.5 | High | CNA (github.com) |
| CVSS 3.1 | 7.5 | High | CNA |
Official description
CoreDNS is a DNS server that chains plugins. Prior to version 1.14.2, a denial of service vulnerability exists in CoreDNS's loop detection plugin that allows an attacker to crash the DNS server by sending specially crafted DNS queries. The vulnerability stems from the use of a predictable pseudo-random number generator (PRNG) for generating a secret query name, combined with a fatal error handler that terminates the entire process. This issue has been patched in version 1.14.2.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Predictable Seed in Pseudo-Random Number Generator (PRNG)
A Pseudo-Random Number Generator (PRNG) is initialized from a predictable seed, such as the process ID or system time.
How developers prevent this class of flaw
- Use non-predictable inputs for seed generation.
- Use products or modules that conform to FIPS 140-2 to avoid obvious entropy problems, or use the more recent FIPS 140-3 if possible.
- Use a PRNG that periodically re-seeds itself using input from high-quality sources, such as hardware devices with high entropy. However, do not re-seed too frequently, or else the entropy source might block.
More Predictable Seed in Pseudo-Random Number Generator (PRNG) vulnerabilities (CWE-337)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Patches and release notes
- github.com/coredns/coredns/releases/tag/v1.14.2Product, Release Notes
Other references
Other vulnerabilities in coredns
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- 7.5 High severity
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- 9.8 Critical severity
- 7.5 High severity
- 7.5 High severity
Recent Predictable Seed in Pseudo-Random Number Generator (PRNG) vulnerabilities
- 7.5 High severity
- 8.3 High severity
- 8.7 High severity
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