CVE-2026-81928
Description
A flaw was found in Net::DNS versions before 1.57 for Perl. An attacker can cause a denial of service (DoS) by sending a specially crafted DNS message with a misplaced Transaction Signature (TSIG) record. When a system using Net::DNS, such as a forwarder or proxy, attempts to re-encode this message, it can lead to unbounded recursion and memory exhaustion, ultimately terminating the process. This vulnerability arises because the sig_data function fails to properly remove TSIG records from all sections of a DNS message, violating RFC 8945 section 5.2 requirements.
Mitigation
To mitigate this issue, restrict network access to DNS services utilizing `perl-Net-DNS` to trusted clients or internal networks only, thereby limiting exposure. If the DNS service is not required to act as a forwarder or proxy, disable this functionality to prevent the vulnerable code path from being exercised.
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 | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Amplification
An infinite loop will cause unexpected consumption of resources, such as CPU cycles or memory. The software's operation may slow down, or cause a long time to respond.
Frequently Asked Questions
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