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Fencer Intel
medium 5.6

CVE-2026-19542 json

Stack-based out-of-bounds write in tdelete during tree rebalancing

published last mo. modified last mo. also EUVD-2026-77685

cvss
5.6
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 13%
public exploits
0
none known

Summary

Calling tdelete on a sufficiently deep tree in the GNU C Library version 2.1 to 2.44 may write one pointer past the end of an alloca-allocated array on the stack, which may crash the application.

The tdelete implementation keeps an explicit stack of parent nodes for rebalancing, which is grown as needed while descending the tree. Two rebalancing branches push an additional entry without checking the capacity, and write past the array when the stack is exactly full. Triggering this requires a node at a depth of exactly 40 (or 40 plus a multiple of 20), which implies a tree with at least a million nodes, so an attacker must drive a large number of insertions and deletions through an application that uses tsearch and tdelete. The written value is a pointer into a tree node and is not directly attacker controlled. No affected application in common distributions has been identified.

Patch / fix

  • glibc Debian 14 2.43-4

debian advisories DEBIAN-CVE-2026-19542

  • glibc Ubuntu 22.04 LTS 2.35-0ubuntu3.15
  • glibc Ubuntu 24.04 LTS 2.39-0ubuntu8.9
  • glibc Ubuntu 26.04 LTS 2.43-2ubuntu2.4

ubuntu advisories UBUNTU-CVE-2026-19542

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • glibc RHEL 8 2.28-251.el8_10.48
  • nscd RHEL 8 2.28-251.el8_10.48
  • libnsl RHEL 8 2.28-251.el8_10.48
  • nss_db RHEL 8 2.28-251.el8_10.48
  • nss_hesiod RHEL 8 2.28-251.el8_10.48
  • glibc-utils RHEL 8 2.28-251.el8_10.48
  • glibc-common RHEL 8 2.28-251.el8_10.48
  • glibc-benchtests RHEL 8 2.28-251.el8_10.48

red hat advisories RHSA-2026:80798RHSA-2026:79281RHSA-2026:76781RHSA-2026:59721

  • 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 8 2.28-251.el8_10.48
  • nscd AlmaLinux 8 2.28-251.el8_10.48
  • libnsl AlmaLinux 8 2.28-251.el8_10.48
  • nss_db AlmaLinux 8 2.28-251.el8_10.48
  • nss_hesiod AlmaLinux 8 2.28-251.el8_10.48
  • glibc-utils AlmaLinux 8 2.28-251.el8_10.48
  • glibc-common AlmaLinux 8 2.28-251.el8_10.48
  • glibc-benchtests AlmaLinux 8 2.28-251.el8_10.48

almalinux advisories ALSA-2026:80798ALSA-2026:79281ALSA-2026:76781

  • glibc Rocky Linux 8 2.28-251.el8_10.48
  • glibc Rocky Linux 10 2.39-142.el10_2
  • glibc Rocky Linux 9 2.34-283.el9_8

rocky linux advisories RLSA-2026:80798RLSA-2026:76781RLSA-2026:79281

Is CVE-2026-19542 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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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-2026-19542 updated cvss 4.2

glibc: Fix out-of-bounds array write in tdelete

  • 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 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 Cost Management 4 costmanagement/costmanagement-metrics-rhel9-operator 1793202662
    fixed: vendor fix RHSA-2026:95264
  • 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 2.39-142.el10_2, glibc-locale-source 2.39-142.el10_2
    fixed: vendor fix RHSA-2026:76781
  • 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
  • Red Hat Enterprise Linux BaseOS (v. 10) glibc 2.39-142.el10_2, libnsl 2.39-142.el10_2, glibc-common 2.39-142.el10_2, glibc-gconv-extra 2.39-142.el10_2, glibc-all-langpacks 2.39-142.el10_2, glibc-minimal-langpack 2.39-142.el10_2
    fixed: vendor fix RHSA-2026:76781
show 6 more
  • 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 2.39-142.el10_2, nss_hesiod 2.39-142.el10_2, glibc-benchtests 2.39-142.el10_2
    fixed: vendor fix RHSA-2026:76781
  • 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 2.43-8.2.hum1, libnsl 2.43-8.2.hum1, nss_db 2.43-8.2.hum1, glibc32 2.43-8.2.hum1, nss_hesiod 2.43-8.2.hum1, glibc-utils 2.43-8.2.hum1, +9 more
    fixed: vendor fix RHSA-2026:59721
  • 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 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
last mo.

Exploit prediction

0.23% chance of exploitation in the next 30 days, higher than 13% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 5.6 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

Affected products

  • The GNU C Library glibc

Classification

Weakness
  • CWE-121 Stack-based Buffer Overflow

References

Sources

Fencer Intel 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.