CVE intelligence and bounded remediation

CVE-2021-20257 — An infinite loop flaw was found in the e1000 NIC emulator of the QEMU

Medium CVSS 6.5

An infinite loop flaw was found in the e1000 NIC emulator of the QEMU. This issue occurs while processing transmits (tx) descriptors in process_tx_desc if various descriptor fields are initialized with invalid values. This flaw allows a guest to consume CPU cycles on the host, resulting in a denial of service. The highest threat from this vulnerability is to system availability.

Severity
Medium
CVSS
6.5 (3.1)
Published
2022-03-16
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-835

Affected products

  • qemu / qemu
  • fedoraproject / fedora / 33
  • redhat / openstack_platform / 10.0
  • redhat / openstack_platform / 13.0
  • redhat / enterprise_linux / 6.0
  • redhat / enterprise_linux / 8.0

Showing 6 representative product identities from 11 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Resource exhaustion and denial of service

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Identify attacker-influenced work factors including input size, nesting, compression, fan-out, regex cost, allocation, recursion, retries, and connection lifetime.
  • Map per-request and shared CPU, memory, disk, descriptor, thread, queue, and downstream-service limits.
  • Determine whether authentication, tenancy, quotas, and rate controls apply before expensive processing begins.

Remediate safely

  • Bound input size, nesting, expansion, work, concurrency, queue depth, retries, and execution time before resource-intensive processing.
  • Release resources on every success, error, cancellation, and timeout path and use backpressure instead of unbounded buffering.
  • Update affected components and add small deterministic tests that assert resource ceilings rather than exhausting a host.

Authoritative sources

Complete CVE record and remediation plan

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