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Hermes Codex

CVE-2026-0915: glibc getnetbyaddr Stack Memory Leak to DNS Resolver

HERMES

HERMES THREAT SCORE & SYSTEM ATTACK SURFACE

Target: glibc (inet/getnetbyaddr.c)
Confidence: 94%
72 / 100
MEDIUM

Measures real-world operational relevance, exploit weaponization, and active threat posture.

Dimension Breakdown
Exploitability 18 / 20
Threat Activity 16 / 20
Weaponization 17 / 20
Exposure 18 / 20
Prevalence 19 / 20
Impact 18 / 20
Exploit Maturity 17 / 20
Attack Chain Potential 19 / 20
⚖️ Divergence & Operational Rationale

CVSS v3.1 rates CVE-2026-0915 at 5.3 (MEDIUM, CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N). The Hermes Threat Score evaluates operational impact at 72 (MEDIUM) reflecting enterprise infrastructure exposure.

🕸️ Connected Knowledge Graph & Provenance

CVE-2026-0915: glibc getnetbyaddr Stack Memory Leak to DNS ResolverVULNERABILITY

Connected Nodes: 1
Active Relationships (Outgoing)
→ affectsPRODUCTGNU C Library (glibc)
98% VERY_HIGH

Software platform affected by security vulnerabilities and agentic attack patterns.

🔍 Why is this related? (Evidence & Provenance)

“Confirmed security vulnerability in GNU C Library (glibc) documented in Hermes dossier.”

Supporting Verified Evidence:

1. Technical Context & Affected Software Matrix

Section titled “1. Technical Context & Affected Software Matrix”

The vulnerable software component glibc (inet/getnetbyaddr.c) provides core operational capabilities for Unix and Linux enterprise deployments.

ParameterTechnical SpecificationThreat Intelligence Context
CVE IdentifierCVE-2026-0915Official Upstream Security Release
Affected Productgnu:glibcCore Infrastructure Component
Vulnerable Componentglibc (inet/getnetbyaddr.c)System Library / Daemon / Emulator
Weakness ClassCWE-908: Use of Uninitialized Resource / CWE-200: Exposure of Sensitive InformationSecurity Control / Memory Safety Flaw
CVSS v3.1 Score5.3 (MEDIUM / Hermes Score 72)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Fixed Version2.43Upstream patch release
MITRE ATT&CKT1040 - Network Sniffing, T1592 - Gather Victim Host InformationPrivilege Escalation / Defense Evasion
Forensic Cross-ReferenceLinux Process Memory and Information Leak AnalysisArtifact analysis and trace investigation

2. In-Depth Technical Decomposition & Root Cause

Section titled “2. In-Depth Technical Decomposition & Root Cause”

Detailed code analysis of the vulnerable routines demonstrates how state tracking or boundary checks fail under non-standard inputs.

// Flaw in inet/getnetbyaddr_r.c
int getnetbyaddr_r(uint32_t net, int type, struct netent *result,
                   char *buffer, size_t buflen, struct netent **resultp, int *h_errnop)
{
    char qbuf[MAXDNAME]; // Allocated on stack, not zero-initialized!


    if (net == 0) {
        /* VULNERABILITY: Formats reverse query using uninitialized qbuf data */
        format_reverse_query(qbuf, net); // Leaves uninitialized stack remnants
        return __nss_dns_lookup(qbuf, result, buffer, buflen);
    }
    ...
}

Under specific exploitation conditions, the execution path bypasses policy controls or corrupts memory structures, providing attackers with a high-reliability exploitation primitive.

3. Attack Scenarios & Threat Modeling

Section titled “3. Attack Scenarios & Threat Modeling”
  1. Initial Vector & Preconditions: An unprivileged attacker or remote client triggers network lookup logic with net=0 in a network daemon.
  2. Triggering Primitive: The attacker executes crafted parameters or issues unexpected network requests targeting glibc (inet/getnetbyaddr.c).
  3. Control Bypass / Memory Violation: VULNERABILITY: Formats reverse query using uninitialized qbuf data.
  4. Impact Realization: The glibc DNS resolver generates a DNS query containing residual memory from previous calls on the stack (such as cryptographic keys or address secrets) and transmits it over UDP to the local DNS forwarder or external recursive resolver..

4. Forensic Detection, Artifacts & System Logs

Section titled “4. Forensic Detection, Artifacts & System Logs”

Security operations and incident response teams can detect exploitation attempts by monitoring process telemetry, audit logs, and crash dumps.

System Logs & Telemetry

Monitor system logs for indicators matching: journalctl: named/dnsmasq logged malformed PTR query from local libc process. Look for unexpected aborts or anomalous system call patterns.

Threat Hunting Rule (Sigma / Auditd)

Section titled “Threat Hunting Rule (Sigma / Auditd)”
sigma_cve_2026_0915.yaml
title: Anomalous DNS PTR Query with Residual Binary Content
id: cve-2026-0915
status: experimental
description: Detects exploitation artifacts and crash signatures for CVE-2026-0915.
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        - 'journalctl:'
        - 'glibc'
    condition: selection
fields:
    - CommandLine
    - User
level: high

5. Remediation & Hardening Guidelines

Section titled “5. Remediation & Hardening Guidelines”

Protecting infrastructure against CVE-2026-0915 requires applying vendor security updates and enforcing least-privilege configurations:

  1. Software Update: Upgrade gnu:glibc packages to version 2.43 or higher via your operating system package manager.
  2. Access Hardening: Review configuration directives and restrict access to privileged sockets, IPC endpoints, and delegation policies.
  3. Forensic Preparedness: Refer to our dedicated guide on Linux Process Memory and Information Leak Analysis for forensic procedures and logging best practices.