CVE-2026-106558

HIGHPre-NVD 8.88.8
EchelonGraph scoreLOW confidence

This high-severity CVE scores 8.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: secondary
8.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: —CVSS: 8.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Backstage is an open framework for building developer portals. Prior to 1.14.8, 1.15.6, and 2.0.1, the @backstage/plugin-techdocs-node package improperly validated mapping-style markdown_extensions configuration. An authenticated attacker who can register or influence an SCM-backed documentation source may bypass TechDocs sanitization and cause Python objects to be imported and instantiated in the generator runtime, leading to arbitrary code execution. Earlier fixes in versions 1.14.6 and 1.15.4 did not fully address the supported mapping representation of markdown_extensions. Impact is greatest when documentation generation runs with backend credentials, filesystem access, or internal network access. This issue is fixed in versions 1.14.8, 1.15.6, and 2.0.1.

CVSS v3
8.8
EG Score
8.8HIGHlow confidence
EG Risk
44
EG Risk 44/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity88% × 45%
Exploitation0% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track or Attend at high (mission-essential systems).
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
—
EPSS %ILE
—
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track or 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 none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

October 7, 2026

Last Modified

October 7, 2026

Advisory Details (7)

Auto-updated Oct 7, 2026
Patch available. Sources: github, github_commit, github_release.
github_release Patch Available

v1.55.2

Patch available: backstage/backstage v1.55.2

https://github.com/backstage/backstage/releases/tag/v1.55.2
github_release Patch Available

v1.54.9

Patch available: backstage/backstage v1.54.9

https://github.com/backstage/backstage/releases/tag/v1.54.9
github_release Patch Available

v1.50.7

Patch available: backstage/backstage v1.50.7

https://github.com/backstage/backstage/releases/tag/v1.50.7
github_commit Patch Available

commit f18e9abcc605 (backstage/backstage)

Patch available: backstage/backstage v1.54.9 (contains commit f18e9abcc605)

https://github.com/backstage/backstage/commit/f18e9abcc6051491862b15e4fc60e69f8d52310c
github_commit Patch Available

commit 944edb51c852 (backstage/backstage)

Patch available: backstage/backstage v1.55.2 (contains commit 944edb51c852)

https://github.com/backstage/backstage/commit/944edb51c8524d3664b18f2d57ba101b1c93b709
github_commit Patch Available

commit 32723a0fe4e1 (backstage/backstage)

Patch available: backstage/backstage v1.50.7 (contains commit 32723a0fe4e1)

https://github.com/backstage/backstage/commit/32723a0fe4e12ed80535fc65d5331765c55aa91b
githubMentions a patch (unverified)

Improper validation of TechDocs MkDocs configuration · Advisory · backstage/backstage · GitHub

https://github.com/backstage/backstage/security/advisories/GHSA-qmw3-745m-w99g

Vendor Advisories for CVE-2026-106558(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 3× in last 7d / 3× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

  1. 2026-10-07 15:30 UTCEG score recompute
  2. 2026-10-07 14:52 UTCEG score recompute
  3. 2026-10-07 14:51 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(4)

What is CVE-2026-106558?
CVE-2026-106558 is a high vulnerability published on October 7, 2026. Backstage is an open framework for building developer portals. Prior to 1.14.8, 1.15.6, and 2.0.1, the @backstage/plugin-techdocs-node package improperly validated mapping-style markdownextensions configuration. An authenticated attacker who can register or influence an SCM-backed documentation…
When was CVE-2026-106558 disclosed?
CVE-2026-106558 was first published on October 7, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
What is the CVSS score of CVE-2026-106558?
CVE-2026-106558 has a CVSS base score of 8.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2026-106558?
A fix for CVE-2026-106558 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-106558 are linked in the Vendor Advisories panel on this page.

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