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Fencer Intel
high 7.5

CVE-2026-45623 json

PostCSS: Arbitrary file read and information disclosure via attacker-controlled sourceMappingURL in CSS comments

published 3mo ago modified last mo. also EUVD-2026-49376 , GHSA-6g55-p6wh-862q

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 49%
public exploits
0
none known

Summary

PostCSS takes a CSS file and provides an API to analyze and modify its rules by transforming the rules into an Abstract Syntax Tree. In versions 8.5.11 and prior, the PreviousMap parses the /*# sourceMappingURL=PATH */ comment from any CSS string passed to process() and dereferences PATH against the local filesystem with no scheme, allowlist, or traversal check. An attacker who controls the CSS input can cause the host process to read any file readable by Node and leak the first ~10 bytes of its content through the resulting JSON.parse SyntaxError message. The bug also yields a precise file-existence oracle and a controllable-read primitive that may be combined with large-file targets for DoS. The behaviour is triggered with PostCSS's default options — no from, no map, no plugins required — and is therefore reachable from any pipeline that runs untrusted CSS through PostCSS (CMS themes, user-uploaded styles, browser-extension/userstyle processors, build pipelines for third-party packages, blog comment renderers, etc.). This issue has been fixed in version 8.5.12.

Patch / fix

  • npm postcss 8.5.12
  • postcss postcss 8.5.12
  • node-postcss Debian 14 8.5.12+~cs9.3.32-1

debian advisories DEBIAN-CVE-2026-45623

  • foreman satellite utils 6.19, satellite capsule 6.19, satellite 6.19 3.18.0.14-1.el9sat
  • foreman-cli satellite utils 6.19, satellite 6.19 3.18.0.14-1.el9sat
  • foreman-ec2 satellite 6.19 3.18.0.14-1.el9sat
  • foreman-pcp satellite capsule 6.19, satellite 6.19 3.18.0.14-1.el9sat
  • foreman-redis satellite 6.19 3.18.0.14-1.el9sat
  • foreman-vmware satellite 6.19 3.18.0.14-1.el9sat
  • foreman-libvirt satellite 6.19 3.18.0.14-1.el9sat
  • foreman-service satellite 6.19 3.18.0.14-1.el9sat

red hat advisories RHSA-2026:74503RHSA-2026:57590

  • velociraptor openSUSE Tumbleweed 0.76.7.0.git145.b60ef1146-1.1

opensuse advisories openSUSE-SU-2026:12070-1

Is CVE-2026-45623 in your dependencies? 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-2026-45623 updated cvss 7.5

postcss: PostCSS: Information disclosure and denial of service via crafted CSS input

  • Red Hat Migration Toolkit for Containers rhmtc/openshift-migration-ui-rhel8 Red Hat Node HealthCheck Operator workload-availability/node-healthcheck-rhel9-operator, workload-availability/node-healthcheck-operator-bundle, workload-availability/node-healthcheck-must-gather-rhel9 Red Hat OpenShift Lightspeed openshift-lightspeed/lightspeed-agentic-console-rhel9 Red Hat OpenShift Pipelines openshift-pipelines/pipelines-hub-ui-rhel8, openshift-pipelines/pipelines-hub-ui-rhel9, openshift-pipelines/pipelines-console-plugin-rhel8, openshift-pipelines/pipelines-console-plugin-rhel9, openshift-pipelines/pipelines-console-plugin-pf5-rhel9
    affected: no fix available
  • Red Hat Ansible Automation Platform 2 automation-eda-controller 1.0.11-1.el9ap
    affected: no fix planned “Will not fix”
  • Red Hat build of Apache Camel - HawtIO 4 postcss 8.5.12 Red Hat build of Apicurio Registry 3 apicurio/apicurio-registry-ui-rhel8 Red Hat Build of Keycloak postcss 8.5.12 Red Hat Build of Podman Desktop rh-podman-desktop.git 1.1.0 Red Hat Connectivity Link 1 rhcl-1/rhcl-console-plugin-rhel9
    affected: no fix available
  • Red Hat Enterprise Linux 9 goose, goose 1.23.2-2.el10_2 Red Hat Enterprise Linux 10 goose 1.23.2-2.el10_2
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux AI (RHEL AI) 3 rhelai3/bootc-cuda-rhel9, rhelai3/bootc-rocm-rhel9, rhelai3/bootc-gaudi-rhel9, rhelai3/disk-image-cuda-rhel9
    affected: no fix available, no fix planned “Will not fix”
  • Red Hat JBoss Enterprise Application Platform 7 postcss 8.5.12
    affected: no fix planned “Will not fix”
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-mlflow-rhel9 Red Hat Openshift Data Foundation 4 odf4/odf-console-rhel9 Red Hat Quay 3 quay/quay-rhel8 Red Hat Satellite 6 nodejs-sanitize-html 2.3.2-1.el9sat
    affected: no fix available
  • Red Hat Single Sign-On 7 postcss 8.5.12
    affected: no fix planned “Will not fix”
show 21 more
  • Red Hat streams for Apache Kafka 3 postcss 8.5.12
    affected: no fix available
  • Red Hat Cluster Observability Operator 1.5 cluster-observability-operator/prometheus-rhel9 1790857922
    fixed: vendor fix RHSA-2026:74609
  • Red Hat multicluster engine for Kubernetes 2.8 multicluster-engine/console-mce-rhel9 1787259048
    fixed: vendor fix RHSA-2026:59558
  • Red Hat multicluster engine for Kubernetes 2.9 multicluster-engine/console-mce-rhel9 1787079359
    fixed: vendor fix RHSA-2026:59559
  • Red Hat multicluster engine for Kubernetes 2.11 multicluster-engine/console-mce-rhel9 1786911977
    fixed: vendor fix RHSA-2026:57194
  • Red Hat multicluster engine for Kubernetes 2.17 multicluster-engine/console-mce-rhel9 1786668856
    fixed: vendor fix RHSA-2026:59593
  • Red Hat Advanced Cluster Management for Kubernetes 2.11 rhacm2/console-rhel9 1787687062
    fixed: vendor fix RHSA-2026:60387
  • Red Hat Advanced Cluster Management for Kubernetes 2.13 rhacm2/console-rhel9 1787339249
    fixed: vendor fix RHSA-2026:60390
  • Red Hat Advanced Cluster Management for Kubernetes 2.14 rhacm2/console-rhel9 1787339248
    fixed: vendor fix RHSA-2026:60388
  • Red Hat Advanced Cluster Management for Kubernetes 2.15 rhacm2/console-rhel9 1786547771
    fixed: vendor fix RHSA-2026:54427
  • Red Hat Advanced Cluster Management for Kubernetes 2.16 rhacm2/console-rhel9 1786908361
    fixed: vendor fix RHSA-2026:57191
  • Red Hat Advanced Cluster Management for Kubernetes 2.17 rhacm2/console-rhel9 1787335105
    fixed: vendor fix RHSA-2026:60386
  • Red Hat Ansible Automation Platform 2.1 ansible-automation-platform/automation-portal 1787047114
    fixed: vendor fix RHSA-2026:56338
  • Red Hat Ansible Automation Platform 2.2 ansible-automation-platform/automation-portal 1787047188
    fixed: vendor fix RHSA-2026:56357
  • Red Hat Discovery 2 discovery/discovery-ui-rhel9 1788206196
    fixed: vendor fix RHSA-2026:61783
  • Red Hat Enterprise Linux Extensions Channel (v. 10) rh-podman-desktop 1.1.2-1.el10_2
    fixed: vendor fix RHSA-2026:57590
  • Red Hat OpenShift AI 2.25 rhoai/odh-dashboard-rhel9 1788312226, rhoai/odh-mod-arch-model-registry-rhel9 1788312157
    fixed: vendor fix RHSA-2026:65126
  • Red Hat OpenShift AI 3.4 rhoai/odh-dashboard-rhel9 1787347991, rhoai/odh-mod-arch-maas-rhel9 1787251250, rhoai/odh-mod-arch-automl-rhel9 1787250508, rhoai/odh-mod-arch-gen-ai-rhel9 1786611759, rhoai/odh-mod-arch-mlflow-rhel9 1786612219, rhoai/odh-mod-arch-autorag-rhel9 1787251550, +2 more
    fixed: vendor fix RHSA-2026:60520
  • Red Hat OpenShift Container Platform 4.14 openshift4/ose-console 1789332071
    fixed: vendor fix RHSA-2026:67838
  • Red Hat OpenShift Container Platform 4.15 openshift4/ose-console 1789369299
    fixed: vendor fix RHSA-2026:67858
  • Red Hat OpenShift Container Platform 4.16 openshift4/ose-console-rhel9 1789453727
    fixed: vendor fix RHSA-2026:67936

16 more fixed, 53 more not affected in the full advisory

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
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
3mo ago

Exploit prediction

0.61% chance of exploitation in the next 30 days, higher than 49% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/postcss/postcss/security/advisories/GHSA-6g55-p6wh-862q referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Affected packages

ecosystem package affected fixed in
npm postcss
<8.5.12
8.5.12

Affected products

  • postcss postcss

Classification

Weakness
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory
  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor

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.