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PatchSiren cyber security CVE debrief

CVE-2026-34933 avahi CVE debrief

CVE-2026-34933 is a denial of service vulnerability in Avahi, a system facilitating service discovery on local networks. Prior to version 0.9-rc4, an unprivileged local user can crash avahi-daemon by sending a single D-Bus method call with conflicting publish flags. This issue has been patched in version 0.9-rc4. The vulnerability allows an attacker to cause a denial of service, potentially disrupting service discovery and other network operations. Users of affected systems should apply the patch to prevent local denial of service attacks.

Vendor
avahi
Product
Unknown
CVSS
MEDIUM 5.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-04-03
Original CVE updated
2026-07-24
Advisory published
2026-04-03
Advisory updated
2026-07-24

Who should care

Users of Avahi versions prior to 0.9-rc4 should apply the patch to prevent local denial of service attacks. This includes operators of systems using Avahi for service discovery, as well as security teams responsible for vulnerability management. Affected platforms may include Linux systems and other environments where Avahi is deployed.

Technical summary

Avahi is a system which facilitates service discovery on a local network via the mDNS/DNS-SD protocol suite. Prior to version 0.9-rc4, any unprivileged local user can crash avahi-daemon by sending a single D-Bus method call with conflicting publish flags. This issue has been patched in version 0.9-rc4. The vulnerability is characterized by CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H, with a CVSS score of 5.5 and a severity of MEDIUM. The patch addresses the issue by properly handling publish flags, preventing denial of service attacks.

Defensive priority

Apply the patch to prevent local denial of service attacks.

Recommended defensive actions

  • Apply the patch to prevent local denial of service attacks.
  • Restrict access to avahi-daemon to trusted users.
  • Monitor avahi-daemon logs for suspicious activity.
  • Review compensating controls for exposed systems while remediation is scheduled and verified.
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review.
  • Track exceptions, retest remediated assets, and close the item only after evidence is documented.
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The CVE record was published on 2026-04-03T23:17:05.377Z and was last modified on 2026-07-24T22:10:00.140Z. The NVD entry is currently Analyzed. Evidence is limited to public sources and may not reflect the full scope of affected systems or potential impact. Defenders should verify the vulnerability's relevance to their environment and review official advisories for specific guidance.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-34933 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-34933

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-34933 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-34933

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.