CVE-2023-2911 | Exceeding the recursive-clients quota may cause named to terminate unexpectedly when stale-answer-client-timeout is set to 0

If the `recursive-clients` quota is reached on a BIND 9 resolver configured with both `stale-answer-enable yes;` and `stale-answer-client-timeout 0;`, a sequence of serve-stale-related lookups could cause `named` to loop and terminate unexpectedly due to a stack overflow. This issue affects BIND 9 versions 9.16.33 through 9.16.41, 9.18.7 through 9.18.15, 9.16.33-S1 through 9.16.41-S1, and 9.18.11-S1 through 9.18.15-S1.

Published: 2023-06-21 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-2911 is rated Moderate Risk (59.4/100): CVSS High severity, with medium exploitation likelihood (EPSS 2.57%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2023-2911

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-22 2.31% 2.57% +0.27%
2 2026-06-15 0.13% 2.31% +2.18%
3 2026-06-05 — 0.13% —

Full EPSS history (20 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-2911

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2023-2911

OS Trackers for CVE-2023-2911

vendor priority summary link
alpine high CVE-2023-2911: 1 source package rows (bind); 20 state rows across 5 repos (3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 0, open 20. https://security.alpinelinux.org/vuln/CVE-2023-2911
debian not yet assigned CVE-2023-2911 not yet assigned priority: Debian including 1 source packages (bind9), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2023-2911
redhat medium — https://access.redhat.com/security/cve/CVE-2023-2911
suse high CVE-2023-2911 severity important: SUSE including 292 source package names (amazon/suse-sles-15-sp1-chost-byos-v20210304-hvm-ssd-x86_64, amazon/suse-sles-15-sp1-chost-byos-v20220127-hvm-ssd-x86_64, …), 857 product×package rows across 161 product lines (Image SLES15-SP4-BYOS, Image SLES15-SP4-BYOS-Azure, … (161 product lines)): Known Not Affected 359, Fixed 332, Known Affected 166. https://www.suse.com/security/cve/CVE-2023-2911/
ubuntu medium CVE-2023-2911 medium priority: Ubuntu including 3 source packages (bind9, bind9-libs, isc-dhcp), 34 status rows across 12 suites (bionic, focal, jammy, kinetic, lunar, mantic, noble, oracular, plucky, trusty, upstream, xenial): not-affected 14, released 9, DNE 7, ignored 2, needs-triage 2. https://ubuntu.com/security/CVE-2023-2911

Affected software / configurations for CVE-2023-2911

Vendor Product Version Raw CPE
isc bind >= 9.16.33, <= 9.16.41 cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*
isc bind >= 9.16.33, <= 9.16.41 cpe:2.3:a:isc:bind:*:*:*:*:supported_preview:*:*:*
isc bind >= 9.18.7, <= 9.18.15 cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:*
isc bind >= 9.18.11, <= 9.18.15 cpe:2.3:a:isc:bind:*:*:*:*:supported_preview:*:*:*
debian debian_linux 11.0 cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
debian debian_linux 12.0 cpe:2.3:o:debian:debian_linux:12.0:*:*:*:*:*:*:*
fedoraproject fedora 37 cpe:2.3:o:fedoraproject:fedora:37:*:*:*:*:*:*:*
fedoraproject fedora 38 cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:*
netapp active_iq_unified_manager — cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:vmware_vsphere:*:*
netapp h700s_firmware — cpe:2.3:o:netapp:h700s_firmware:-:*:*:*:*:*:*:*
netapp h300s_firmware — cpe:2.3:o:netapp:h300s_firmware:-:*:*:*:*:*:*:*
netapp h410c_firmware — cpe:2.3:o:netapp:h410c_firmware:-:*:*:*:*:*:*:*
netapp h410s_firmware — cpe:2.3:o:netapp:h410s_firmware:-:*:*:*:*:*:*:*
netapp h500s_firmware — cpe:2.3:o:netapp:h500s_firmware:-:*:*:*:*:*:*:*

References for CVE-2023-2911

cvelogic Threat Intelligence