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Fencer Vulns
medium 4.9

CVE-2026-18374 json

Passing an effectively empty string to the `,ccs=` syntax extension of the mode argument in the `fopen` function in the GNU C Library versi…

published 2026-08-27 2 mo ago modified 2026-09-03 2 mo ago also EUVD-2026-67222

cvss
4.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 3%
public exploits
0
none known

Summary

Passing an effectively empty string to the `,ccs=` syntax extension of the mode argument in the `fopen` function in the GNU C Library version 2.45 or earlier may result in a heap buffer overflow when the mode string input to the function is attacker controlled.

This usage pattern is not seen in applications in common GNU/Linux distributions and applications that process user-supplied values for `ccs` should not pass them through without validation.

Patch / fix

  • The GNU C Library glibc 2.45
  • glibc Debian 14 2.43-5

debian advisories DEBIAN-CVE-2026-18374

  • 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-2026:80798RHSA-2026:79281RHSA-2026:65339

  • 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
  • glibc SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Development Tools 15 SP7 +1 more 2.38-150600.14.58.1
  • glibc Linux Micro 6.1 2.38-slfo.1.1_10.1
  • glibc Linux Micro 6.0 2.38-15.1
  • glibc SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 2.22-114.52.2

suse advisories SUSE-SU-2026:4591-1SUSE-SU-2026:23934-1SUSE-SU-2026:23957-1SUSE-SU-2026:23929-1SUSE-SU-2026:4250-1SUSE-SU-2026:4204-1

  • 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
  • glibc openSUSE Tumbleweed 2.44-2.1

opensuse advisories openSUSE-SU-2026:21968-1openSUSE-SU-2026:11787-1

  • glibc AlmaLinux 10 2.39-145.el10_2.alma.1
  • libnsl AlmaLinux 10 2.39-145.el10_2.alma.1
  • nss_db AlmaLinux 10 2.39-145.el10_2.alma.1
  • nss_hesiod AlmaLinux 10 2.39-145.el10_2.alma.1
  • glibc-utils AlmaLinux 10 2.39-145.el10_2.alma.1
  • glibc-common AlmaLinux 10 2.39-145.el10_2.alma.1
  • glibc-benchtests AlmaLinux 10 2.39-145.el10_2.alma.1
  • glibc-gconv-extra AlmaLinux 10 2.39-145.el10_2.alma.1

almalinux advisories ALSA-2026:84753ALSA-2026:80798ALSA-2026:79281

  • glibc Rocky Linux 10 2.39-145.el10_2
  • glibc Rocky Linux 8 2.28-251.el8_10.48
  • glibc Rocky Linux 9 2.34-283.el9_8

rocky linux advisories RLSA-2026:84753RLSA-2026:80798RLSA-2026:79281

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-2026-18374 updated cvss 4.9

glibc: glibc: Heap buffer overflow via attacker-controlled fopen mode string

  • 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
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Cost Management 4 costmanagement/costmanagement-metrics-rhel9-operator 1793202662
    fixed: vendor fix RHSA-2026:95264
  • 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_10.48, compat-libpthread-nonshared 2.28-251.el8_10.48
    fixed: vendor fix RHSA-2026:80798
  • Red Hat Enterprise Linux AppStream (v. 9) glibc-utils 2.34-283.el9_8, glibc-locale-source 2.34-283.el9_8
    fixed: vendor fix RHSA-2026:79281
  • 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_10.48, glibc 2.28-251.el8_10.48, libnsl 2.28-251.el8_10.48, nss_db 2.28-251.el8_10.48, glibc-common 2.28-251.el8_10.48, glibc-gconv-extra 2.28-251.el8_10.48, +3 more
    fixed: vendor fix RHSA-2026:80798
  • Red Hat Enterprise Linux BaseOS (v. 9) nscd 2.34-283.el9_8, glibc 2.34-283.el9_8, libnsl 2.34-283.el9_8, glibc-common 2.34-283.el9_8, glibc-gconv-extra 2.34-283.el9_8, glibc-all-langpacks 2.34-283.el9_8, +1 more
    fixed: vendor fix RHSA-2026:79281
show 9 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 2.34-283.el9_8, nss_hesiod 2.34-283.el9_8, glibc-benchtests 2.34-283.el9_8
    fixed: vendor fix RHSA-2026:79281
  • 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_10.48, glibc-benchtests 2.28-251.el8_10.48
    fixed: vendor fix RHSA-2026:80798
  • Red Hat Hardened Images glibc 2.43-8.5.hum1, libnsl 2.43-8.5.hum1, nss_db 2.43-8.5.hum1, glibc32 2.43-8.5.hum1, nss_hesiod 2.43-8.5.hum1, glibc-utils 2.43-8.5.hum1, +9 more
    fixed: vendor fix RHSA-2026:65339
  • Red Hat Update Infrastructure 5 rhui5/cds-rhel9 1791978528, rhui5/rhua-rhel9 1791978693, rhui5/haproxy-rhel9 1791978528, rhui5/installer-rhel9 1791964013, rhui5/cds-kubernetes-rhel9 1791978534
    fixed: vendor fix RHSA-2026:82939
  • Red Hat Cost Management 4 costmanagement/costmanagement-metrics-operator-bundle 1793205914
    not affected: vulnerable code not present
  • Red Hat Hardened Images filesystem
    not affected: component not present
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-kserve-controller-rhel9, rhoai/odh-model-serving-api-rhel9, rhoai/odh-workbenches-operator-rhel9, rhoai/odh-llama-stack-k8s-operator-rhel9, rhoai/odh-kserve-llmisvc-controller-rhel9
    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
2 mo ago

Exploit prediction

0.14% chance of exploitation in the next 30 days, higher than 3% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 4.9 CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.