avahi: Multicast DNS responds to unicast queries outside of local network
Published May 1, 2017
9.1
CRITICALCVSS 3.1
EPSS 3.24%
Description
avahi-daemon in Avahi through 0.6.32 and 0.7 inadvertently responds to IPv6 unicast queries with source addresses that are not on-link, which allows remote attackers to cause a denial of service (traffic amplification) and may cause information leakage by obtaining potentially sensitive information from the responding device via port-5353 UDP packets. NOTE: this may overlap CVE-2015-2809.
Affected products
No data.
Configuration 2
- 12.04
- 14.04
- 16.04
- 18.04
- 18.10
No data.
Red Hat Enterprise Linux 7
avahi-0:0.6.31-20.el7
Fixed · RHSA-2020:1176
Red Hat Enterprise Linux 5
avahi
Will not fix
Red Hat Enterprise Linux 6
avahi
Will not fix
Red Hat Enterprise Linux 8
avahi
Will not fix
Red Hat Enterprise Linux 9
avahi
Affected
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 7 | avahi-0:0.6.31-20.el7 | Fixed | RHSA-2020:1176 |
| Red Hat Enterprise Linux 5 | avahi | Will not fix | n/a |
| Red Hat Enterprise Linux 6 | avahi | Will not fix | n/a |
| Red Hat Enterprise Linux 8 | avahi | Will not fix | n/a |
| Red Hat Enterprise Linux 9 | avahi | Affected | n/a |
No package ranges for this CVE.
Remediation
Red Hat statement
This vulnerability is rated as low severity because it allows a remote attacker to cause a denial of service or amplify traffic through crafted UDP packets, it could impact availability, it does not pose a significant risk to system integrity or confidentiality.
Red Hat mitigation
Ensure UDP port 5353 is blocked in the firewall. Moreover, configure correctly the rate limiting options based on your needs (see ratelimit-interval-usec and ratelimit-burst options in /etc/avahi/avahi-daemon.conf).
Metrics
No CVSS v4.0 score for this CVE.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
1 other source (Red Hat) ▾
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L
AV:N/AC:L/Au:N/C:P/I:N/A:P
This CVE is not in the KEV list.
CISA SSVC (Vulnrichment)
Stakeholder-Specific Vulnerability Categorization from CISA ADP.
Exploitation
NoneAutomatable
YesTechnical Impact
PartialDecision
n/aAssessed Dec 3, 2025 · SSVC 2.0.3
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
2021–2026- EPSS v1
- EPSS v5
- EPSS v2
- EPSS v3
- EPSS v4
Percentile over time
- EPSS v1
- EPSS v5
- EPSS v2
- EPSS v3
- EPSS v4
Table of values (14 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 3.24% (0.03238) | 87.85th | v5 (v2026.06.15) |
| Jun 15, 2026 | 3.08% (0.03082) | 85.94th | v5 (v2026.06.15) |
| Mar 30, 2025 | 2.03% (0.02030) | 82.19th | v4 (v2025.03.14) |
| Mar 29, 2025 | 3.10% (0.03101) | 77.90th | v4 (v2025.03.14) |
| Mar 17, 2025 | 2.03% (0.02030) | 82.59th | v4 (v2025.03.14) |
| Dec 17, 2024 | 2.09% (0.02091) | 88.80th | v3 (v2023.03.01) |
| Dec 12, 2024 | 5.67% (0.05666) | 93.61th | v3 (v2023.03.01) |
| May 13, 2024 | 5.55% (0.05552) | 93.19th | v3 (v2023.03.01) |
| May 8, 2023 | 4.77% (0.04769) | 91.43th | v3 (v2023.03.01) |
| Mar 7, 2023 | 3.35% (0.03350) | 89.86th | v3 (v2023.03.01) |
| Mar 6, 2023 | 1.32% (0.01319) | 71.27th | v2 (v2022.01.01) |
| Feb 4, 2022 | 1.32% (0.01319) | 44.98th | v2 (v2022.01.01) |
| Feb 3, 2022 | 2.58% (0.02580) | 55.23th | v5 (v2026.06.15) |
| Apr 14, 2021 | 2.58% (0.02580) | 0.00th | v1 |
References (11)
- https://access.redhat.com/security/cve/CVE-2017-6519 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1426712 x_refsource_MISCIssue TrackingPatchThird Party Advisory
- https://github.com/lathiat/avahi/issues/203 x_refsource_MISCExploitThird Party Advisory
- https://github.com/lathiat/avahi/issues/203#issuecomment-449536790 x_refsource_MISCThird Party Advisory
- https://lists.apache.org/thread.html/r1b103833cb5bc8466e24ff0ecc5e75b45a705334ab6a444e64e840a0%40%3Cissues.bookkeeper.apache.org%3E mailing-listx_refsource_MLIST
- https://nvd.nist.gov/vuln/detail/CVE-2017-6519
- https://usn.ubuntu.com/3876-1/ vendor-advisoryx_refsource_UBUNTUThird Party Advisory
- https://usn.ubuntu.com/3876-2/ vendor-advisoryx_refsource_UBUNTUThird Party Advisory
- https://www.cve.org/CVERecord?id=CVE-2017-6519
- https://www.kb.cert.org/vuls/id/550620
- https://www.secfu.net/advisories x_refsource_MISCThird Party Advisory
| Link | Providers | Tags |
|---|---|---|
| https://access.redhat.com/security/cve/CVE-2017-6519 | Vendor Advisory | |
| https://bugzilla.redhat.com/show_bug.cgi?id=1426712 | x_refsource_MISCIssue TrackingPatchThird Party Advisory | |
| https://github.com/lathiat/avahi/issues/203 | x_refsource_MISCExploitThird Party Advisory | |
| https://github.com/lathiat/avahi/issues/203#issuecomment-449536790 | x_refsource_MISCThird Party Advisory | |
| https://lists.apache.org/thread.html/r1b103833cb5bc8466e24ff0ecc5e75b45a705334ab6a444e64e840a0%40%3Cissues.bookkeeper.apache.org%3E | mailing-listx_refsource_MLIST | |
| https://nvd.nist.gov/vuln/detail/CVE-2017-6519 | ||
| https://usn.ubuntu.com/3876-1/ | vendor-advisoryx_refsource_UBUNTUThird Party Advisory | |
| https://usn.ubuntu.com/3876-2/ | vendor-advisoryx_refsource_UBUNTUThird Party Advisory | |
| https://www.cve.org/CVERecord?id=CVE-2017-6519 | ||
| https://www.kb.cert.org/vuls/id/550620 | ||
| https://www.secfu.net/advisories | x_refsource_MISCThird Party Advisory |
Change history (0)
No recorded changes yet.