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Fencer Vulns
medium 5.3

CVE-2026-8674 json

Assertion failure in the DNS stub resolver with a long search domain

published 2026-09-17 52 d ago modified 2026-09-18 51 d ago also EUVD-2026-82326

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 24%
public exploits
0
none known

Summary

Initializing the DNS stub resolver from an /etc/resolv.conf file, or a LOCALDOMAIN environment variable, whose search list contains a domain of roughly 200 characters or more in the GNU C Library version 2.26 to 2.44 results in an assertion failure which aborts the process.

The resolver truncates the search list when copying it into the fixed-size _res.defdname buffer, then asserts that the copy is consistent with the full configuration. The consistency check compared against the wrong size and did not handle a first entry that does not fit, so a correctly truncated list failed the assertion. Any process that resolves names through the library is affected, including long-running processes that reload /etc/resolv.conf on the next query after it changes. Search domains are commonly written to /etc/resolv.conf from data received over DHCP or from a VPN server, so an attacker on the local network may be able to trigger this without privileges on the target system, subject to validation by the network configuration software.

Patch / fix

  • glibc Debian 14 2.43-6

debian advisories DEBIAN-CVE-2026-8674

  • glibc RHEL 10.2 2.39-145.el10_2
  • libnsl RHEL 10.2 2.39-145.el10_2
  • nss_db RHEL 10.2 2.39-145.el10_2
  • nss_hesiod RHEL 10.2 2.39-145.el10_2
  • glibc-utils RHEL 10.2 2.39-145.el10_2
  • glibc-common RHEL 10.2 2.39-145.el10_2
  • glibc-benchtests RHEL 10.2 2.39-145.el10_2
  • glibc-gconv-extra RHEL 10.2 2.39-145.el10_2

red hat advisories RHSA-2026:84753RHSA-2026:69276

  • 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 16.0, Linux Micro Extras 6.2, Linux Micro 6.2 +1 more 2.40-160000.7.1

suse advisories SUSE-SU-2026:24281-1SUSE-SU-2026:24326-1SUSE-SU-2026:4656-1SUSE-SU-2026:4591-1SUSE-SU-2026:23934-1SUSE-SU-2026:23957-1

  • glibc openSUSE Tumbleweed 2.44-3.1
  • glibc openSUSE Leap 16.0 2.40-160000.7.1
  • glibc-cross-s390x-src openSUSE Leap 16.0 2.40-160000.7.1
  • glibc-cross-aarch64-src openSUSE Leap 16.0 2.40-160000.7.1
  • glibc-cross-ppc64le-src openSUSE Leap 16.0 2.40-160000.7.1
  • glibc-cross-riscv64-src openSUSE Leap 16.0 2.40-160000.7.1

opensuse advisories openSUSE-SU-2026:12072-1openSUSE-SU-2026:21968-1

  • 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-2026:95618ALSA-2026:84753

  • glibc Rocky Linux 9 2.34-284.el9_8.4
  • glibc Rocky Linux 10 2.39-145.el10_2

rocky linux advisories RLSA-2026:95618RLSA-2026:84753

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-2026-8674 updated cvss 5.3

glibc: glibc DNS stub resolver: Denial of Service via long search domain in configuration

  • 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 Cost Management On-Premise 1 costmanagement/costmanagement-ui-rhel10 1792605272
    fixed: vendor fix RHSA-2026:87400
  • Red Hat Enterprise Linux AppStream (v. 8) glibc-utils 2.28-251.el8_10.53, compat-libpthread-nonshared 2.28-251.el8_10.53
    fixed: vendor fix RHSA-2026:96087
  • Red Hat Enterprise Linux AppStream (v. 9) glibc-utils 2.34-284.el9_8.4, glibc-locale-source 2.34-284.el9_8.4
    fixed: vendor fix RHSA-2026:95618
  • Red Hat Enterprise Linux AppStream (v. 10) glibc-utils 2.39-145.el10_2, glibc-locale-source 2.39-145.el10_2
    fixed: vendor fix RHSA-2026:84753
  • Red Hat Enterprise Linux BaseOS (v. 8) nscd 2.28-251.el8_10.53, glibc 2.28-251.el8_10.53, libnsl 2.28-251.el8_10.53, nss_db 2.28-251.el8_10.53, glibc-common 2.28-251.el8_10.53, glibc-gconv-extra 2.28-251.el8_10.53, +3 more
    fixed: vendor fix RHSA-2026:96087
  • 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
    fixed: vendor fix RHSA-2026:95618
show 6 more
  • Red Hat Enterprise Linux BaseOS (v. 10) glibc 2.39-145.el10_2, libnsl 2.39-145.el10_2, glibc-common 2.39-145.el10_2, glibc-gconv-extra 2.39-145.el10_2, glibc-all-langpacks 2.39-145.el10_2, glibc-minimal-langpack 2.39-145.el10_2
    fixed: vendor fix RHSA-2026:84753
  • 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 CodeReady Linux Builder (v. 10) nss_db 2.39-145.el10_2, nss_hesiod 2.39-145.el10_2, glibc-benchtests 2.39-145.el10_2
    fixed: vendor fix RHSA-2026:84753
  • Red Hat Enterprise Linux CRB (v. 8) nss_hesiod 2.28-251.el8_10.53, glibc-benchtests 2.28-251.el8_10.53
    fixed: vendor fix RHSA-2026:96087
  • Red Hat Hardened Images glibc 2.43-8.6.hum1, libnsl 2.43-8.6.hum1, nss_db 2.43-8.6.hum1, glibc32 2.43-8.6.hum1, nss_hesiod 2.43-8.6.hum1, glibc-utils 2.43-8.6.hum1, +9 more
    fixed: vendor fix RHSA-2026:69276
  • 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 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
52 d ago

Exploit prediction

0.32% chance of exploitation in the next 30 days, higher than 24% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • The GNU C Library glibc

Classification

Weakness

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.