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CVE-2025-40780: Cache poisoning due to weak PRNG

• Severity: high (CVSS 8.6 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-10-22 · updated 2026-10-08
• Weakness: CWE-341

Description

In specific circumstances, due to a weakness in the Pseudo Random Number Generator (PRNG) that is used, it is possible for an attacker to predict the source port and query ID that BIND will use. This issue affects BIND 9 versions 9.16.0 through 9.16.50, 9.18.0 through 9.18.39, 9.20.0 through 9.20.13, 9.21.0 through 9.21.12, 9.16.8-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.39-S1, and 9.20.9-S1 through 9.20.13-S1.

Affected products

• ISC BIND: from 9.16.0 through 9.16.50; from 9.18.0 through 9.18.39; from 9.20.0 through 9.20.13; from 9.21.0 through 9.21.12; from 9.16.8-S1 through 9.16.50-S1; from 9.18.11-S1 through 9.18.39-S1

References

• https://kb.isc.org/docs/cve-2025-40780
• http://www.openwall.com/lists/oss-security/2025/10/22/1

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