CVE-2026-3593: isc bind Use After Free
CVSS: 9.8v3.1CriticalModified
AliasesALPINE-CVE-2026-3593UBUNTU-CVE-2026-3593DEBIAN-CVE-2026-3593openSUSE-SU-2026:10915-1
Published 20-05-2026Last modified 01-09-2026
Vulnerability summary
CVE-2026-3593 is a critical (CVSS 9.8) Use After Free vulnerability in isc bind. EPSS estimates a 1.09% chance of exploitation in the next 30 days, higher than 64.8% of scored vulnerabilities.
CVSS score
9.8/10
010
Critical · v3.1 (NVD)EPSS score
1.09%
0%100%
Low · -0.45 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 6 · Related 5Timeline
- 20-05-2026PublishedVulnerability first disclosed.
- 01-09-2026Last modifiedVulnerability information updated.
Description
A use-after-free vulnerability exists within the DNS-over-HTTPS implementation. This issue affects BIND 9 versions 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, and 9.20.9-S1 through 9.20.22-S1. BIND 9 versions 9.18.0 through 9.18.48 and 9.18.11-S1 through 9.18.48-S1 are NOT affected.
CVSS metrics
5 scores · 5 sources · 1 versionCritical 9.8Preferred score · NVD (NIST)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HSources5 sources · 7.4–9.8
- CVE.orgCNA7.4HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:HDiffers
- OSV · AlpineEcosystem advisory · calculated9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- OSV · UbuntuEcosystem advisory · calculated9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS trend
Probability
1.09%
Chance of exploitation in the next 30 days
Percentile
65%
Versus all other CVEs
30-day change
-0.45 pp
From 1.54% on 20-09-2026
20-09-202620-10-2026
EPSS score1.09%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-416Use After FreeThe product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
- CWE-825Expired Pointer DereferenceThe product dereferences a pointer that contains a location for memory that was previously valid, but is no longer valid.
Affected systems
Isc2 products
Alpine1 product
- bind≥ 9.20.0, < 9.18.49-r0 | ≥ 9.20.0, < 9.20.23-r0
Debian1 product
- bind9< 1:9.20.23-1~deb13u1 | < 1:9.20.23-1
Opensuse1 product
- bind&distro=openSUSE Tumbleweed< 9.20.23-2.1
Ubuntu1 product
- bind9< 1:9.20.11-1ubuntu2.4 | < 1:9.20.18-1ubuntu2.1
5 vendors · 6 products
