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TI-2021-02461 Aliases CVE-2021-3502GHSA-mw7q-3wxj-rqfx

Reachable assertion in avahi

Priority LOW 25CWE-617Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-617.

Summary

A flaw was found in avahi 0.8-5. A reachable assertion is present in avahi_s_host_name_resolver_start function allowing a local attacker to crash the avahi service by requesting hostname resolutions through the avahi socket or dbus methods for invalid hostnames. The highest threat from this vulnerability is to the service availability.

Why it matters now

EPSS 0.00374 31st percentileScored 2026-11-07
Public exploit Yes 2 exploit referencesTagged by NVD
Fix Fixed Red Hat: 1 advisory

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
—avahi0.8-5—No fix listedCNA
  • avahi Vendor— Affected 0.8-5 Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:avahi:avahi:0.8-5:*:*:*:*:*:*:*0.8-5Vulnerableavahi
  • cpe:2.3:a:avahi:avahi:0.8-5:*:*:*:*:*:*:* Versions 0.8-5 Vulnerable ·avahi

Remediation

Red Hat 1 advisory

  • RHSA-2023:6707 Released 2023-11-07 · Red Hat rating Moderate
    avahi security update
    • Red Hat CodeReady Linux Builder (v. 9) avahi-compat-howl-0.8-15.el9, avahi-compat-howl-devel-0.8-15.el9, avahi-compat-libdns_sd-0.8-15.el9 +3
    • Red Hat Enterprise Linux AppStream (v. 9) avahi-glib-0.8-15.el9, avahi-tools-0.8-15.el9
    • Red Hat Enterprise Linux BaseOS (v. 9) avahi-0.8-15.el9, avahi-libs-0.8-15.el9

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat CodeReady Linux Builder (v. 9)Fixed RHSA-2023:6707
Red Hat Enterprise Linux AppStream (v. 9)Fixed RHSA-2023:6707
Red Hat Enterprise Linux BaseOS (v. 9)Fixed RHSA-2023:6707
Not affected: 3 products
  • Red Hat Enterprise Linux 6
  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-3502
  2. 2026-10-03 Alias added: GHSA-mw7q-3wxj-rqfx

References

Exploit 2

  • TI-2026-27157 Avahi: Reachable assertion in `transport_flags_from_domain()` via conflicting publish flags crashes avahi-daemon CVSS 3.1MEDIUM 5.5
  • TI-2025-37060 Avahi: simple protocol server ignores accepts unlimited connections and logs failures without limit CVSS 3.1MEDIUM 5.5
  • TI-2008-04834 The originates_from_local_legacy_unicast_socket function (avahi-core/server.c) in… CVSS 2.0MEDIUM 5.0
  • TI-2017-04303 avahi-daemon in Avahi through 0.6.32 and 0.7 inadvertently responds to IPv6 unicast… CVSS 3.1CRITICAL 9.1
  • TI-2011-00862 avahi-core/socket.c in avahi-daemon in Avahi before 0.6.29 allows remote attackers to… CVSS 2.0MEDIUM 5.0
  • TI-2021-08399 avahi-daemon-check-dns.sh in the Debian avahi package through 0.8-4 is executed as root… CVSS 3.1HIGH 7.8
See all 23 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences