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.
CVE-2026-45623
“—” beside the score: it is equal to NVD's CVSS score.
This critical-severity CVE scores 9.1 under NVD CVSS v3. EPSS exploit probability: 0.6% (49th percentile of EPSS-scored CVEs). GitHub Security Advisory CVSS 7.5 is lower than this score; a lower GitHub score revises it only when its advisory is newer than the CVE record's last change, and this advisory (published 2026-07-23) is not newer than that change (2026-08-07), so it does not.
Also known asEUVD-2026-49376 (ENISA EUVD) · GHSA-6g55-p6wh-862q (GitHub Security Advisories)Source: ENISA EUVD
- CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
A fix is available — apply it.
- CVSS v3
- 9.1
- EG Score
- 9.1CRITICALmedium confidence
- EG Risk
- 72EG Risk 72/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity91% × 45%Impact severity (EG Severity): CVSS 9.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation40% × 40%EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.Automatability100% × 15%CISA's SSVC Automatable value: yes (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high. - EPSS PROB
- 0.6%
- EPSS %ILE
- 49th
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (9.1): severity, escalated by confirmed exploitation. This CVE's 9.1 is its impact severity (EG Severity), not escalated.
- EG Severity
- 9.1 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
- EG Likelihood
- 0.6% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-01). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
July 23, 2026
Last Modified
August 7, 2026
Advisory Details (1)
Auto-updated Sep 16, 2026Arbitrary file read and information disclosure via attacker-controlled sourceMappingURL in CSS comments · Advisory · postcss/postcss · GitHub
https://github.com/postcss/postcss/security/advisories/GHSA-6g55-p6wh-862qVendor Advisories for CVE-2026-45623(20)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
- RHSA-2026:84734Red Hat Product SecurityCritical
Red Hat Security Advisory: RHOAI 3.4.5 - Red Hat OpenShift AI
- RHSA-2026:83598Red Hat Product SecurityHigh
Red Hat Security Advisory: RHTAS 1.4.4 - Red Hat Trusted Artifact Signer Release
- RHSA-2026:74621Red Hat Product SecurityMedium
Red Hat Security Advisory: General availability of the satellite/iop-advisor-frontend-rhel9 container image
- RHSA-2026:74609Red Hat Product SecurityHigh
Red Hat Security Advisory: Cluster Observability Operator 1.5.3
- RHSA-2026:74503Red Hat Product SecurityCritical
Red Hat Security Advisory: Satellite 6.19.5 Async Update
- RHSA-2026:70587Red Hat Product SecurityHigh
Red Hat Security Advisory: OpenShift Container Platform 4.17.58 bug fix and security update
- RHSA-2026:67858Red Hat Product SecurityHigh
Red Hat Security Advisory: OpenShift Container Platform 4.15.69 bug fix and security update
- RHSA-2026:67838Red Hat Product SecurityHigh
Red Hat Security Advisory: OpenShift Container Platform 4.14.74 bug fix and security update
- +12 more
Patch Availability(31)
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Affected Packages
(5 across 5 ecosystems)
Debian:11(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| node-postcss | 8.2.1+~cs5.3.23-8 ... 8.5.9+~cs9.3.30-1 (31 versions) |
| — |
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| node-postcss | 8.4.20+~cs8.0.23-1 ... 8.5.9+~cs9.3.30-1 (19 versions) |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| node-postcss | 8.4.49+~cs9.2.32-1 ... 8.5.9+~cs9.3.30-1 (15 versions) |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| node-postcss | 8.4.49+~cs9.2.32-1, 8.5.6+~cs9.3.28-1, 8.5.8+~cs9.3.30-1, 8.5.9+~cs9.3.30-1 |
| — |
npm(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| postcss | — |
| — |
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Additional Vendor Advisories
(20)
Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.
- Red HatRHSA-2026:54427MODERATE2026-07-27
RHSA-2026:54427 — Moderate
- Red HatRHSA-2026:56338MODERATE2026-07-27
RHSA-2026:56338 — Moderate
- Red HatRHSA-2026:56357MODERATE2026-07-27
RHSA-2026:56357 — Moderate
- Red HatRHSA-2026:57191MODERATE2026-07-27
RHSA-2026:57191 — Moderate
- Red HatRHSA-2026:57194MODERATE2026-07-27
RHSA-2026:57194 — Moderate
- Red HatRHSA-2026:57590MODERATE2026-07-27
RHSA-2026:57590 — Moderate
- Red HatRHSA-2026:59548MODERATE2026-07-27
RHSA-2026:59548 — Moderate
- Red HatRHSA-2026:59554MODERATE2026-07-27
RHSA-2026:59554 — Moderate
- Red HatRHSA-2026:59558MODERATE2026-07-27
RHSA-2026:59558 — Moderate
- Red HatRHSA-2026:59559MODERATE2026-07-27
RHSA-2026:59559 — Moderate
- Red HatRHSA-2026:59561MODERATE2026-07-27
RHSA-2026:59561 — Moderate
- Red HatRHSA-2026:59566MODERATE2026-07-27
RHSA-2026:59566 — Moderate
- Red HatRHSA-2026:59583MODERATE2026-07-27
RHSA-2026:59583 — Moderate
- Red HatRHSA-2026:59593MODERATE2026-07-27
RHSA-2026:59593 — Moderate
- Red HatRHSA-2026:60386MODERATE2026-07-27
RHSA-2026:60386 — Moderate
- Red HatRHSA-2026:60387MODERATE2026-07-27
RHSA-2026:60387 — Moderate
- Red HatRHSA-2026:60388MODERATE2026-07-27
RHSA-2026:60388 — Moderate
- Red HatRHSA-2026:60390MODERATE2026-07-27
RHSA-2026:60390 — Moderate
- Red HatRHSA-2026:60520MODERATE2026-07-27
RHSA-2026:60520 — Moderate
- Red HatRHSA-2026:61783MODERATE2026-07-27
RHSA-2026:61783 — Moderate
Data Freshness Timeline
(refreshed 24× in last 7d / 83× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
Showing the most recent 100 of 341 refreshes on record for this CVE.
A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 241 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-11-02 02:54 UTCEG score recompute
- 2026-11-02 02:54 UTCVendor advisory
- 2026-11-02 02:54 UTCGHSA enrichmentGHSA-6g55-p6wh-862q · GitHub severity HIGH · GitHub CVSS 7.5
- 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.6% · 49th percentile
- 2026-11-01 07:48 UTCGHSA enrichmentGHSA-6g55-p6wh-862q · GitHub severity HIGH · GitHub CVSS 7.5
- 2026-11-01 07:48 UTCEG score recompute
- 2026-11-01 03:08 UTCEG score recompute
- 2026-11-01 03:08 UTCVendor advisory
- 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.6% · 49th percentile
- 2026-10-31 03:22 UTCEG score recompute
- 2026-10-31 03:22 UTCVendor advisory
- 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.6% · 49th percentile
- 2026-10-30 03:37 UTCEG score recompute
- 2026-10-30 03:37 UTCVendor advisory
- 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
- 2026-10-29 03:52 UTCEG score recompute
- 2026-10-29 03:52 UTCVendor advisory
- 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.6% · 48th percentile
- 2026-10-28 04:05 UTCEG score recompute
- 2026-10-28 04:05 UTCVendor advisory
- 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.6% · 48th percentile
- 2026-10-27 04:04 UTCEG score recompute
- 2026-10-27 04:04 UTCVendor advisory
- 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.6% · 48th percentile
- 2026-10-25 23:59 UTCEG score recompute
Show 75 moreShow fewer
- 2026-10-25 23:59 UTCVendor advisory
- 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
- 2026-10-25 14:26 UTCEG score recompute
- 2026-10-25 00:13 UTCEG score recompute
- 2026-10-25 00:13 UTCVendor advisory
- 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
- 2026-10-24 00:28 UTCEG score recompute
- 2026-10-24 00:28 UTCVendor advisory
- 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.6% · 48th percentile
- 2026-10-23 00:40 UTCEG score recompute
- 2026-10-23 00:40 UTCVendor advisory
- 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.6% · 48th percentile
- 2026-10-22 00:49 UTCEG score recompute
- 2026-10-22 00:49 UTCVendor advisory
- 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
- 2026-10-21 01:04 UTCEG score recompute
- 2026-10-21 01:04 UTCVendor advisory
- 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
- 2026-10-20 01:17 UTCEG score recompute
- 2026-10-20 01:17 UTCVendor advisory
- 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.6% · 48th percentile
- 2026-10-19 00:11 UTCEG score recompute
- 2026-10-19 00:11 UTCVendor advisory
- 2026-10-18 03:38 UTCEG score recompute
- 2026-10-18 00:23 UTCEG score recompute
- 2026-10-18 00:23 UTCVendor advisory
- 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.6% · 48th percentile
- 2026-10-17 00:37 UTCEG score recompute
- 2026-10-17 00:37 UTCVendor advisory
- 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-16 00:27 UTCEG score recompute
- 2026-10-16 00:27 UTCVendor advisory
- 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-14 18:59 UTCEG score recompute
- 2026-10-14 18:59 UTCVendor advisory
- 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-13 15:23 UTCEG score recompute
- 2026-10-13 15:23 UTCVendor advisory
- 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-12 15:34 UTCEG score recompute
- 2026-10-12 15:34 UTCVendor advisory
- 2026-10-12 07:45 UTCVendor advisory
- 2026-10-11 19:46 UTCEG score recompute
- 2026-10-11 17:00 UTCEG score recompute
- 2026-10-11 14:26 UTCEG score recompute
- 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-04 12:43 UTCVendor advisory
- 2026-10-04 08:21 UTCEG score recompute
- 2026-10-04 08:21 UTCVendor advisory
- 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-03 03:24 UTCEG score recompute
- 2026-10-03 03:24 UTCVendor advisory
- 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-10-01 14:28 UTCVendor advisory
- 2026-10-01 10:22 UTCVendor advisory
- 2026-10-01 06:17 UTCEG score recompute
- 2026-10-01 06:17 UTCVendor advisory
- 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.6% · 47th percentile
- 2026-09-28 13:17 UTCVendor advisory
- 2026-09-28 09:11 UTCVendor advisory
- 2026-09-28 05:06 UTCEG score recompute
- 2026-09-28 05:06 UTCVendor advisory
- 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.6% · 46th percentile
- 2026-09-24 11:01 UTCVendor advisory
- 2026-09-24 06:35 UTCVendor advisory
- 2026-09-24 02:29 UTCVendor advisory
Related CVEs(same product + same vendor + same CWE)
Same product
10 shownnpm:postcss · Debian:11:node-postcss
Same vendor
10 shownredhat:RHSA-2026:56338 · redhat:RHSA-2026:57191 · redhat:RHSA-2026:59548
Frequently asked(5)
What is CVE-2026-45623?
When was the CVE record for CVE-2026-45623 published?
Is CVE-2026-45623 actively exploited?
What is the CVSS score of CVE-2026-45623?
How do I remediate CVE-2026-45623?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-45623
Is Your Infrastructure Affected by CVE-2026-45623?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.