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Fencer Vulns
medium 4.2

CVE-2026-89092 json

Stack overflow in nscd due to unbounded alloca use

published 2026-09-11 59 d ago modified 2026-10-26 13 d ago also EUVD-2026-75897

cvss
4.2
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 15%
public exploits
0
none known

Summary

The nscd service in the GNU C Library 2.3.4 onwards may crash due to a stack overflow when a malicious DNS server returns too large a response for a DNS query, resulting in degraded DNS resolution for the system.

Exploitation of this bug needs a system that has nscd enabled and using an untrusted DNS server for name resolution, with the compromised DNS server being capable of processing records large enough to result in a stack overflow in an nscd thread stack.  During experimentation, bind 9 was unable to handle large records, but that could change in future or with a different name server.  In typical installations, nscd is executed in an isolated context as its own user without a shell, due to which any compromise of that service is isolated.

There is a remote possibility of nscd cache corruption if an attacker manages to get the stack pointer into a desired point in the heap, potentially resulting in other caches in nscd being overwritten with corrupt data through the stack overflow, until the buggy code path eventually results in a crash.

Finally, a crash in nscd may result in performance degradation when resolving names, but it does not result in a denial of service.

Patch / fix

  • The GNU C Library glibc 2.45
  • glibc Debian 14 2.43-7

debian advisories DEBIAN-CVE-2026-89092

  • glibc Linux Micro 6.1 2.38-slfo.1.1_11.1
  • glibc Linux Micro 6.0 2.38-159998.1.1
  • glibc SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Development Tools 15 SP7 +1 more 2.38-150600.14.61.1
  • glibc SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +8 more 2.31-150300.109.1
  • glibc SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 2.22-114.55.1

suse advisories SUSE-SU-2026:24281-1SUSE-SU-2026:24326-1SUSE-SU-2026:4656-1SUSE-SU-2026:4654-1SUSE-SU-2026:4591-1

  • glibc AlmaLinux 9 2.34-284.el9_8.4
  • nscd AlmaLinux 9 2.34-284.el9_8.4
  • libnsl AlmaLinux 9 2.34-284.el9_8.4
  • glibc-utils AlmaLinux 9 2.34-284.el9_8.4
  • glibc-gconv-extra AlmaLinux 9 2.34-284.el9_8.4
  • glibc-all-langpacks AlmaLinux 9 2.34-284.el9_8.4
  • glibc-locale-source AlmaLinux 9 2.34-284.el9_8.4
  • glibc-minimal-langpack AlmaLinux 9 2.34-284.el9_8.4

almalinux advisories ALSA-2026:95618

  • glibc Rocky Linux 9 2.34-284.el9_8.4

rocky linux advisories RLSA-2026:95618

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-89092 updated cvss 4.2

glibc: nscd stack overflow leads to degraded DNS resolution

  • Red Hat Enterprise Linux 6 nscd, glibc, glibc-utils, compat-glibc, glibc-common Red Hat Enterprise Linux 7 nscd, glibc, glibc-utils, compat-glibc, glibc-common Red Hat Enterprise Linux 8 nscd, glibc, libnsl, nss_db, nss_hesiod, glibc-utils, +7 more Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9 Red Hat OpenShift Container Platform 5 openshift/ose-rhel-coreos-9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-core-bff-rhel9, rhoai/odh-dashboard-rhel9, rhoai/odh-mod-arch-maas-rhel9, rhoai/odh-mod-arch-automl-rhel9, rhoai/odh-mod-arch-gen-ai-rhel9, rhoai/odh-mod-arch-mlflow-rhel9, +6 more
    under investigation
  • Red Hat Enterprise Linux AppStream (v. 9) glibc-utils 2.34-284.el9_8.4, glibc-locale-source 2.34-284.el9_8.4 Red Hat Enterprise Linux BaseOS (v. 9) nscd 2.34-284.el9_8.4, glibc 2.34-284.el9_8.4, libnsl 2.34-284.el9_8.4, glibc-common 2.34-284.el9_8.4, glibc-gconv-extra 2.34-284.el9_8.4, glibc-all-langpacks 2.34-284.el9_8.4, +1 more Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) nss_db 2.34-284.el9_8.4, nss_hesiod 2.34-284.el9_8.4, glibc-benchtests 2.34-284.el9_8.4
    fixed: vendor fix RHSA-2026:95618
  • Red Hat Enterprise Linux 10 glibc Red Hat Hardened Images glibc
    not affected: component not present
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-mlflow-rhel9, rhoai/odh-kube-rbac-proxy-rhel9, rhoai/odh-maas-controller-rhel9, rhoai/odh-mlflow-operator-rhel9, rhoai/odh-model-controller-rhel9, rhoai/odh-ogx-k8s-operator-rhel9, +14 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
58 d ago

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 15% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 4.2 CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L

Affected products

  • The GNU C Library glibc

Classification

Weakness
  • CWE-789 Memory Allocation with Excessive Size Value

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.