CVE-2023-4527

What it actually does

Memory corruption in glibc getaddrinfo when processing oversized TCP DNS responses (>2048 bytes) under AF_UNSPEC with no-aaaa resolv.conf mode, resulting in stack content disclosure and possible process crash.

Why it matters to the business

Limited risk of information leakage or application instability on affected Linux distributions and appliances; low urgency given age, modest EPSS growth, and lack of KEV or ransomware use, though widespread glibc deployment across enterprise and embedded systems increases exposure surface.

How an attack unfolds

An attacker controls a DNS server or MITM path and responds to a getaddrinfo(AF_UNSPEC) query with a large TCP DNS packet; the flawed parsing leaks stack data or crashes the calling process. Public exploit code exists and the vulnerability has been referenced in threat actor discussions.

How to fix it

Upgrade glibc to the latest vendor-patched release on all affected Red Hat Enterprise Linux, Fedora, and NetApp systems; rebuild and restart dependent applications; enforce TCP DNS size limits or disable no-aaaa where operationally feasible until patches are applied.

How to confirm the fix worked

Verify glibc package versions against vendor advisories, run regression tests exercising getaddrinfo with large TCP responses in no-aaaa mode, and confirm absence of crashes or anomalous address data in test outputs.

Typical attack path

1. Position attacker-controlled DNS responder or intercept traffic
2. Trigger target application call to getaddrinfo with AF_UNSPEC
3. Deliver crafted TCP DNS response exceeding 2048 bytes under no-aaaa configuration
4. Observe stack disclosure in returned address data or induced crash

How to detect it

Review application and system logs for segmentation faults or abnormal terminations during DNS resolution, inspect network captures for oversized TCP DNS responses to clients using getaddrinfo, and correlate with process crashes on systems configured with no-aaaa.

What your security team should do

• Prioritize patching glibc on internet-facing or high-value systems within standard change windows
• Monitor EPSS and exploit availability trends for any increase in observed activity
• Audit resolv.conf configurations for no-aaaa usage and assess necessity
• Include glibc version checks in vulnerability scanning and asset inventory