CVE-2026-77939

MEDIUMPre-NVD 6.56.5—
EchelonGraph scoreHIGH confidence

Score 6.5 from GitHub Security Advisory (severity: HIGH) published 2026-08-28. the CNA's CVSS baseline 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cna:vulncheck, ghsa
Trending — 4 sources updated this weekElevated
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.5Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Flextype CMS through v1.0.0-dev contains an expression language injection vulnerability that allows authenticated attackers with a valid API token to read arbitrary files by passing unsanitized user-supplied input to the Symfony ExpressionLanguage engine via the POST /api/v1/query endpoint. Attackers can leverage exposed application objects including filesystem() and serializers() within the evaluation scope to read arbitrary server files and achieve conditional remote code execution if a PHP file can be placed on disk through a secondary vector.

CVSS v3
6.5
EG Score
6.5(high)
EG Risk
45(Track)
EG Risk 45/100SSVC: Track

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
Severity65% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
37%
KEV
Not listed

Published

August 28, 2026

Last Modified

August 29, 2026

Advisory Details (2)

Auto-updated Aug 28, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic

Flextype CMS 1.0.0-dev RCE via POST /api/v1/query Endpoint | Advisories | VulnCheck

https://www.vulncheck.com/advisories/flextype-cms-dev-rce-via-post-api-v1-query-endpoint
generic🟡 PoC Available

CVE-2026-77939: Server-Side Expression Injection in REST API · Issue #595 · flextype/flextype · GitHub

https://github.com/flextype/flextype/issues/595

Vendor Advisories for CVE-2026-77939(1)

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

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 8× 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. 2026-08-30 01:22 UTCEPSS rescore
  2. 2026-08-29 11:58 UTCEG score recompute
  3. 2026-08-29 11:58 UTCGHSA enrichment
  4. 2026-08-28 22:48 UTCEG score recompute
  5. 2026-08-28 22:47 UTCGHSA enrichment
  6. 2026-08-28 20:25 UTCEG score recompute
  7. 2026-08-28 19:39 UTCEG score recompute
  8. 2026-08-28 19:36 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-77939?
CVE-2026-77939 is a medium vulnerability published on August 28, 2026. Flextype CMS through v1.0.0-dev contains an expression language injection vulnerability that allows authenticated attackers with a valid API token to read arbitrary files by passing unsanitized user-supplied input to the Symfony ExpressionLanguage engine via the POST /api/v1/query endpoint.…
When was CVE-2026-77939 disclosed?
CVE-2026-77939 was first published in the National Vulnerability Database on August 28, 2026, with the most recent update on August 29, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-77939 actively exploited?
CVE-2026-77939 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 63.1% of all scored CVEs.
What is the CVSS score of CVE-2026-77939?
CVE-2026-77939 has a CVSS v4.0 base score of 6.5 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-77939?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-77939, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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