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CVE-2026-3591— A stack use-after-return flaw in SIG(0) handling code may enable ACL bypass

Quick assessment

Affected
ISC BIND 9
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

ISC BIND 9是ISC组织的一个域名系统软件。 ISC BIND 9 9.20.0至9.20.20版本、9.21.0至9.21.19版本和9.20.9-S1至9.20.20-S1版本存在安全漏洞，该漏洞源于处理使用SIG(0)签名的DNS查询时存在释放后重用，可能导致访问控制列表错误匹配IP地址。

CVSS 5.4 · Medium EPSS 0.32% · P23
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I. Basic Information for CVE-2026-3591

Vulnerability Information
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Vulnerability Title
A stack use-after-return flaw in SIG(0) handling code may enable ACL bypass
Source: CVE Program / CVE List V5
Vulnerability Description
A use-after-return vulnerability exists in the `named` server when handling DNS queries signed with SIG(0). Using a specially-crafted DNS request, an attacker may be able to cause an ACL to improperly (mis)match an IP address. In a default-allow ACL (denying only specific IP addresses), this may lead to unauthorized access. Default-deny ACLs should fail-secure. This issue affects BIND 9 versions 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, and 9.20.9-S1 through 9.20.20-S1. BIND 9 versions 9.18.0 through 9.18.46 and 9.18.11-S1 through 9.18.46-S1 are NOT affected.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
返回栈上的变量地址
Source: CVE Program / CVE List V5
Vulnerability Title
ISC BIND 9 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
ISC BIND 9是ISC组织的一个域名系统软件。 ISC BIND 9 9.20.0至9.20.20版本、9.21.0至9.21.19版本和9.20.9-S1至9.20.20-S1版本存在安全漏洞，该漏洞源于处理使用SIG(0)签名的DNS查询时存在释放后重用，可能导致访问控制列表错误匹配IP地址。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
ISC BIND 9 9.20.0 ~ 9.20.20 -

II. Public POCs for CVE-2026-3591

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III. Intelligence Information for CVE-2026-3591

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Patches & Fixes for CVE-2026-3591 (1)

Vendor Advisories for CVE-2026-3591 (1)

Vendor Pages for CVE-2026-3591 (1)

Same Patch Batch · ISC · 2026-03-25 · 5 CVEs total

CVE-2026-3608 7.5 HIGH Stack overflow in Kea daemons
CVE-2026-3104 7.5 HIGH Memory leak in code preparing DNSSEC proofs of non-existence
CVE-2026-1519 7.5 HIGH Excessive NSEC3 iterations cause high CPU load during insecure delegation validation
CVE-2026-3119 6.5 MEDIUM Authenticated query containing a TKEY record may cause named to terminate unexpectedly

IV. Related Vulnerabilities

Same product: BIND 9
Same vendor: ISC
Same weakness: CWE-562

V. Comments for CVE-2026-3591

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