CVE-2026-77939

MEDIUMPre-NVD 6.56.5—
EchelonGraph scoreHIGH confidence

Score 6.5 from GitHub Security Advisory (severity: HIGH) published 2026-08-28. a secondary CVSS source baseline 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 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
38%
KEV
Not listed

Published

August 28, 2026

Last Modified

September 8, 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 18× in last 7d / 63× 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. 2026-09-19 07:41 UTCEG score recompute
  2. 2026-09-19 07:40 UTCGHSA enrichment
  3. 2026-09-18 19:28 UTCEPSS rescore
  4. 2026-09-18 06:51 UTCEG score recompute
  5. 2026-09-18 06:51 UTCGHSA enrichment
  6. 2026-09-17 06:02 UTCEG score recompute
  7. 2026-09-17 06:02 UTCGHSA enrichment
  8. 2026-09-16 14:08 UTCEPSS rescore
  9. 2026-09-16 05:15 UTCEPSS rescore
  10. 2026-09-16 04:50 UTCGHSA enrichment
  11. 2026-09-15 04:01 UTCEG score recompute
  12. 2026-09-15 04:01 UTCGHSA enrichment
  13. 2026-09-15 03:12 UTCEPSS rescore
  14. 2026-09-15 03:12 UTCEPSS rescore
  15. 2026-09-14 03:09 UTCEG score recompute
  16. 2026-09-14 03:09 UTCGHSA enrichment
  17. 2026-09-13 02:20 UTCEG score recompute
  18. 2026-09-13 02:20 UTCGHSA enrichment
  19. 2026-09-12 01:30 UTCEG score recompute
  20. 2026-09-12 01:30 UTCGHSA enrichment
  21. 2026-09-11 14:53 UTCEPSS rescore
  22. 2026-09-11 14:53 UTCEPSS rescore
  23. 2026-09-11 00:41 UTCEG score recompute
  24. 2026-09-11 00:41 UTCGHSA enrichment
  25. 2026-09-10 09:35 UTCEPSS rescore
Show 38 more
  1. 2026-09-09 23:52 UTCEG score recompute
  2. 2026-09-09 23:52 UTCGHSA enrichment
  3. 2026-09-08 22:01 UTCEPSS rescore
  4. 2026-09-08 20:52 UTCEG score recompute
  5. 2026-09-08 20:51 UTCGHSA enrichment
  6. 2026-09-07 19:47 UTCEG score recompute
  7. 2026-09-07 19:47 UTCGHSA enrichment
  8. 2026-09-06 18:58 UTCEG score recompute
  9. 2026-09-06 18:58 UTCGHSA enrichment
  10. 2026-09-06 13:48 UTCEPSS rescore
  11. 2026-09-05 18:09 UTCEG score recompute
  12. 2026-09-05 18:08 UTCGHSA enrichment
  13. 2026-09-04 17:14 UTCEG score recompute
  14. 2026-09-04 17:14 UTCGHSA enrichment
  15. 2026-09-04 05:07 UTCEPSS rescore
  16. 2026-09-03 16:25 UTCGHSA enrichment
  17. 2026-09-02 15:35 UTCEG score recompute
  18. 2026-09-02 15:35 UTCGHSA enrichment
  19. 2026-09-02 14:12 UTCEPSS rescore
  20. 2026-09-01 14:35 UTCEG score recompute
  21. 2026-09-01 14:35 UTCGHSA enrichment
  22. 2026-09-01 13:54 UTCEPSS rescore
  23. 2026-09-01 04:40 UTCEPSS rescore
  24. 2026-09-01 04:40 UTCEPSS rescore
  25. 2026-08-31 13:41 UTCEG score recompute
  26. 2026-08-31 13:40 UTCGHSA enrichment
  27. 2026-08-30 19:18 UTCEPSS rescore
  28. 2026-08-30 19:17 UTCEPSS rescore
  29. 2026-08-30 12:49 UTCEG score recompute
  30. 2026-08-30 12:49 UTCGHSA enrichment
  31. 2026-08-30 01:22 UTCEPSS rescore
  32. 2026-08-29 11:58 UTCEG score recompute
  33. 2026-08-29 11:58 UTCGHSA enrichment
  34. 2026-08-28 22:48 UTCEG score recompute
  35. 2026-08-28 22:47 UTCGHSA enrichment
  36. 2026-08-28 20:25 UTCEG score recompute
  37. 2026-08-28 19:39 UTCEG score recompute
  38. 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 September 8, 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 62.0% of all scored CVEs.
What is the CVSS score of CVE-2026-77939?
CVE-2026-77939 has a CVSS v3 base score of 6.5 (NVD).
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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