Actively exploited vulnerability
ISC BIND: denial of service flaw under attack
CVE-2015-5477 · ISC BIND Data Processing Errors Vulnerability
What is affected
ISC BIND is mostly run by companies, schools and public bodies, not on home computers. You are unlikely to have it yourself, but organisations that hold your data may. Breaches that start with flaws like this one are how personal data ends up leaked.
ISC BIND contains a data processing errors vulnerability that could allow remote attackers to cause a denial of service via TKEY queries.
What an attacker can do
This is a denial of service flaw. It lets an attacker crash the product or make it unavailable to the people who rely on it.
- How it is reached
- Over the internet or network
- Access the attacker needs
- No account needed
- Does the victim have to do something?
- No, works without the victim doing anything
What to do
- At home: nothing to install. Keep your own devices updated and use a different password for every service, so that a breach at one organisation does not open your other accounts.
- If you administer ISC BIND at work: apply the vendor's fix or mitigation now and review logs for signs of compromise, because the flaw was being exploited before it was listed.
- If the product is past its support date and no fix exists, take it off the internet or retire it.
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
Vendor advisories and fixes
- web.archive.orgweb.archive.org/web/20150729014733/https://kb.isc.org/article/AA-01272
- access.redhat.comaccess.redhat.com/errata/RHSA-2015:1513.html
- supportportal.juniper.netsupportportal.juniper.net/s/article/2016-01-Security-Bulletin-Junos-Vulnerability-in-ISC-B
How urgent is it
CISA added this vulnerability to its Known Exploited Vulnerabilities catalogue on October 8, 2026, which means there is reliable evidence of attacks in the wild. US federal agencies must fix it by October 11, 2026 (2 days from now). That deadline does not bind anyone else, but it shows how seriously the agency rates it.
The EPSS model estimates a 91% probability that this flaw will be exploited somewhere in the next 30 days. That is higher than 99.8% of all scored vulnerabilities.
Its CVSS severity score is 7.5 out of 10 (high), as recorded in the US National Vulnerability Database.
Technical description
named in ISC BIND 9.x before 9.9.7-P2 and 9.10.x before 9.10.2-P3 allows remote attackers to cause a denial of service (REQUIRE assertion failure and daemon exit) via TKEY queries.