CVE-2021-3502
CVE-2021-3502 is a medium-severity vulnerability in Avahi with a CVSS 3.x base score of 5.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-617.
Key facts
- Severity: Medium (CVSS 3.x base score 5.5)
- CVSS v2: 2.1
- EPSS exploit prediction: 0% (29th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-617
- Affected product: Avahi
- Published:
- Last modified:
Description
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.
Frequently asked questions
- What is CVE-2021-3502?
- 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.
- How severe is CVE-2021-3502?
- CVE-2021-3502 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
- Is CVE-2021-3502 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (29th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2021-3502?
- CVE-2021-3502 affects Avahi. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2021-3502?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- When was CVE-2021-3502 published?
- CVE-2021-3502 was published on 2021-05-07 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:a:avahi:avahi:0.8-5:*:*:*:*:*:*:*
More vulnerabilities in Avahi
- CVE-2017-6519 — Critical (CVSS 9.1): avahi-daemon in Avahi through 0.6.32 and 0.7 inadvertently responds to IPv6 unicast queries with source addresses that…
- CVE-2021-26720 — High (CVSS 7.8): avahi-daemon-check-dns.sh in the Debian avahi package through 0.8-4 is executed as root via…
- CVE-2026-24401 — Medium (CVSS 6.5): Avahi is a system which facilitates service discovery on a local network via the mDNS/DNS-SD protocol suite. In…
- CVE-2025-68471 — Medium (CVSS 6.5): Avahi is a system which facilitates service discovery on a local network via the mDNS/DNS-SD protocol suite. In 0.9-rc2…
- CVE-2025-68468 — Medium (CVSS 6.5): Avahi is a system which facilitates service discovery on a local network via the mDNS/DNS-SD protocol suite. In 0.9-rc2…
- CVE-2023-38473 — Medium (CVSS 6.2): A vulnerability was found in Avahi. A reachable assertion exists in the avahi_alternative_host_name() function.
Other CWE-617 (Reachable Assertion) vulnerabilities
- CVE-2020-3615 — Critical (CVSS 9.8): Valid deauth/disassoc frames is dropped in case if RMF is enabled and some rouge peer keep on sending rogue…
- CVE-2019-9795 — Critical (CVSS 9.8): A vulnerability where type-confusion in the IonMonkey just-in-time (JIT) compiler could potentially be used by…
- CVE-2026-31739 — High (CVSS 8.8): In the Linux kernel, the following vulnerability has been resolved: crypto: tegra - Add missing CRYPTO_ALG_ASYNC The…
- CVE-2020-12417 — High (CVSS 8.8): Due to confusion about ValueTags on JavaScript Objects, an object may pass through the type barrier, resulting in…
- CVE-2020-6623 — High (CVSS 8.8): stb stb_truetype.h through 1.22 has an assertion failure in stbtt__cff_get_index.
- CVE-2020-6619 — High (CVSS 8.8): stb stb_truetype.h through 1.22 has an assertion failure in stbtt__buf_seek.