CVE-2026-48487
Description
A flaw was found in Zeroconf, a Python library for multicast DNS service discovery. An unauthenticated attacker on the local network can exploit a vulnerability in how the system processes incoming DNS records. By sending a specially crafted record with an excessive length, the attacker can cause the system's DNS cache and service information to be populated with manipulated or truncated data. This could lead to incorrect service discovery or other data integrity issues within the affected system.
Statement
Zeroconf is a pure Python implementation of multicast DNS (mDNS) service discovery. Prior to 0.149.16, the record string/character-string readers advance the parser offset using an attacker-declared RDLENGTH without checking it against the actual buffer length, allowing a malformed TXT, HINFO, or A/AAAA record to corrupt subsequent record parsing, resulting in data integrity impact for unauthenticated hosts on the local network segment (UDP/5353, 224.0.0.251 / ff02::fb). Exploitation requires the attacker to be on the same local link as the affected host, consistent with Red Hat's Adjacent (AV:A) attack vector scoring. This issue is fixed upstream in zeroconf 0.149.16.
Red Hat's CVSS score matches the vendor/CVE.org assessment for this flaw. This flaw is one of a batch of related Zeroconf issues discovered and fixed close together (CVE-2026-47180, CVE-2026-47183, CVE-2026-47184, CVE-2026-48045, CVE-2026-48487); all affect the same Red Hat product streams in the same way and were triaged consistently as a batch.
Mitigation
Upgrade to zeroconf 0.149.16 or later once packaged in the affected Red Hat product. Where upgrading isn't immediately possible, restricting the affected host's exposure to the local network segment (network segmentation or firewalling multicast DNS traffic on UDP/5353) reduces the practical attack surface, since exploitation requires local-link access.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 4.3 | 5.3 | N/A |
| Attack Vector | Adjacent Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | Low | Low | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Understanding the Weakness (CWE)
Integrity,Confidentiality,Availability
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
Buffer overflows often can be used to execute arbitrary code, which is usually outside the scope of the product's implicit security policy. This can often be used to subvert any other security service.
Availability
Technical Impact: Modify Memory; DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU)
Buffer overflows generally lead to crashes. Other attacks leading to lack of availability are possible, including putting the product into an infinite loop.
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