CVE-2026-55573

CRITICALPre-NVD 9.89.8
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This critical-severity CVE scores 9.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.7% (53rd percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
Elevated

Also known asEUVD-2026-101532 (ENISA EUVD)Source: ENISA EUVD

9.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.7%CVSS: 9.8Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

e107 is a content management system (CMS). Prior to 2.3.7, install.php decodes the attacker-controlled previous_steps POST parameter and passes it to unserialize() at file scope and again in the e_install constructor without restricting allowed classes. The installer remains accessible after a normal installation, and a crafted object graph using the bundled GuzzleHttp\Psr7\PumpStream class can flow through paths.hash into site_path, where string coercion invokes an attacker-controlled callable. An unauthenticated attacker who can reach install.php can therefore execute arbitrary PHP functions with the web server process's privileges, leading to full server compromise. This issue is fixed in version 2.3.7.

CVSS v3
9.8
EG Score
9.8CRITICALmedium confidence
EG Risk
75
EG Risk 75/100

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)
Severity98% × 45%
Impact severity (EG Severity): CVSS 9.8 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, Track* at medium and Attend at high mission impact.
Exploitation public PoC (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (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
0.7%
EPSS %ILE
53rd
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 (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.

EG Severity
9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
EG Likelihood
0.7% 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, Track* at medium and Attend at high mission impact.CISA BOD 26-04: 3 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, Track* at medium and Attend at high mission impact.

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 total (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)3 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 total (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

October 14, 2026

Last Modified

October 16, 2026

Advisory Details (4)

Auto-updated Oct 28, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_release, github.
GitHub advisoryMentions a patch (unverified)🟡 PoC Available

Unsafe deserialization in install.php allows unauthenticated RCE via POP chain · Advisory · e107inc/e107 · GitHub

https://github.com/e107inc/e107/security/advisories/GHSA-c8h6-wpj3-4cr8
GitHub release Patch Available

e107 v2.3.7

Patch available: e107inc/e107 v2.3.7

https://github.com/e107inc/e107/releases/tag/v2.3.7
GitHub commit

commit 6c4042952139 (e107inc/e107)

Fix landed in e107inc/e107 commit 6c4042952139 — awaiting tagged release

https://github.com/e107inc/e107/commit/6c404295213952aedb9b3689be19dd4c7ba550b0
GitHub commit

commit 5d6d649e8cf0 (e107inc/e107)

Fix landed in e107inc/e107 commit 5d6d649e8cf0 — awaiting tagged release

https://github.com/e107inc/e107/commit/5d6d649e8cf01854d6024d07997c2449fdd75f24

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 14× in last 7d / 43× 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.

  1. 2026-11-02 10:24 UTCEG score recompute
  2. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  3. 2026-11-01 12:29 UTCEG score recompute
  4. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  5. 2026-10-30 16:41 UTCEG score recompute
  6. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  7. 2026-10-29 18:47 UTCEG score recompute
  8. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  9. 2026-10-28 20:53 UTCEG score recompute
  10. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  11. 2026-10-27 22:59 UTCEG score recompute
  12. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  13. 2026-10-27 01:02 UTCEG score recompute
  14. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  15. 2026-10-25 23:22 UTCEG score recompute
  16. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  17. 2026-10-25 14:18 UTCEG score recompute
  18. 2026-10-25 01:25 UTCEG score recompute
  19. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  20. 2026-10-24 03:31 UTCEG score recompute
  21. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  22. 2026-10-23 05:37 UTCEG score recompute
  23. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  24. 2026-10-22 07:43 UTCEG score recompute
  25. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
Show 18 more
  1. 2026-10-21 09:46 UTCEG score recompute
  2. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  3. 2026-10-20 11:52 UTCEG score recompute
  4. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  5. 2026-10-19 13:54 UTCEG score recompute
  6. 2026-10-18 03:30 UTCEG score recompute
  7. 2026-10-17 18:01 UTCEG score recompute
  8. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  9. 2026-10-16 20:07 UTCEG score recompute
  10. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  11. 2026-10-16 14:57 UTCEG score recompute
  12. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  13. 2026-10-15 16:27 UTCEG score recompute
  14. 2026-10-15 15:32 UTCEG score recompute
  15. 2026-10-15 15:23 UTCEG score recompute
  16. 2026-10-14 18:25 UTCEG score recompute
  17. 2026-10-14 18:17 UTCEG score recomputeFirst assessed: 9.8 CRITICAL
  18. 2026-10-14 18:15 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-55573?
CVE-2026-55573 is a critical-severity vulnerability; its CVE record was published on October 14, 2026. e107 is a content management system (CMS). Prior to 2.3.7, install.php decodes the attacker-controlled previous_steps POST parameter and passes it to unserialize() at file scope and again in the e_install constructor without restricting allowed classes. The installer remains accessible after a…
When was the CVE record for CVE-2026-55573 published?
The CVE record for CVE-2026-55573 was published on October 14, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 16, 2026; the record at its source may have been updated since.
Is CVE-2026-55573 actively exploited?
CVE-2026-55573 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.7% probability of exploitation in the next 30 days (53rd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-55573?
CVE-2026-55573 has a CVSS base score of 9.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-55573?
A fix for CVE-2026-55573 is available: update to the fixed version the vendor names in its advisory.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-55573

Explore →

Is Your Infrastructure Affected by CVE-2026-55573?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.