CVE-2026-103956

CRITICALPre-NVD 10.010.0
EchelonGraph scoreMEDIUM confidence

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

This critical-severity CVE scores 10.0 under the CNA's CVSS (NVD's own analysis pending). EPSS exploit probability: 2.5% (84th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from the CNA's CVSS
Sources: the CNA's CVSS, EPSS
Elevated

Also known asEUVD-2026-91770 (ENISA EUVD)Source: ENISA EUVD

10.0EG
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).
  • Public exploit or proof-of-concept code is available
CISA-KEV: Not listedEPSS PROB: 2.5%CVSS: 10.0Exploit: Public PoCExposed services: Not assessed

A fix is available — apply it.

Missing authentication for critical function in the authentication dependency in Loom for AWS before 1.6.1 allowed remote actors to obtain super-admin authority over the agent control plane, including registering tool servers, reading stored integration credentials, and rewriting the IAM role policies attached to managed agent roles, via any request to the application API in a deployment where no identity provider is configured.

To remediate this issue, users should upgrade to version 1.6.1 or later.

CVSS v3
10.0
EG Score
10.0CRITICALmedium confidence
EG Risk
76
EG Risk 76/100

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)
Severity100% × 45%
Impact severity (EG Severity): CVSS 10.0 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 none (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
2.5%
EPSS %ILE
84th
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 (10.0): severity, escalated by confirmed exploitation. This CVE's 10.0 is its impact severity (EG Severity), not escalated.

EG Severity
10.0 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.the CNA's CVSS · CVSS v3.0 or v3.1
EG Likelihood
2.5% 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: 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 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 none (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 2, 2026

Last Modified

October 9, 2026

Advisory Details (3)

Auto-updated Oct 30, 2026
Patch available. Sources: github_release, github.
GitHub advisoryMentions a patch (unverified)

Missing authentication for critical function in Loom for AWS · Advisory · awslabs/loom · GitHub

https://github.com/awslabs/loom/security/advisories/GHSA-vgmj-998f-r8mp
Web page

CVE-2026-103956, CVE-2026-103957, and CVE-2026-103958 - Issues in Loom for AWS

https://aws.amazon.com/security/security-bulletins/2026-124-aws/
GitHub release Patch Available

v1.6.1

Patch available: awslabs/loom v1.6.1

https://github.com/awslabs/loom/releases/tag/v1.6.1

Vendor Advisories for CVE-2026-103956(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 13× in last 7d / 63× 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 16:43 UTCEPSS rescoreEPSS 2.5% · 84th percentile
  2. 2026-11-02 10:16 UTCEG score recompute
  3. 2026-11-01 16:33 UTCEPSS rescoreEPSS 2.5% · 84th percentile
  4. 2026-11-01 08:54 UTCEG score recompute
  5. 2026-10-31 16:31 UTCEPSS rescoreEPSS 2.5% · 84th percentile
  6. 2026-10-31 07:36 UTCEG score recompute
  7. 2026-10-30 16:33 UTCEPSS rescoreEPSS 2.5% · 84th percentile
  8. 2026-10-30 06:18 UTCEG score recompute
  9. 2026-10-29 16:32 UTCEPSS rescoreEPSS 2.5% · 84th percentile
  10. 2026-10-29 05:00 UTCEG score recompute
  11. 2026-10-28 16:31 UTCEPSS rescoreEPSS 2.5% · 84th percentile
  12. 2026-10-28 03:42 UTCEG score recompute
  13. 2026-10-27 16:31 UTCEPSS rescoreEPSS 2.5% · 84th percentile
  14. 2026-10-27 02:10 UTCEG score recompute
  15. 2026-10-26 16:30 UTCEPSS rescoreEPSS 2.5% · 84th percentile
  16. 2026-10-25 20:49 UTCEG score recompute
  17. 2026-10-25 16:32 UTCEPSS rescoreEPSS 2.5% · 84th percentile
  18. 2026-10-25 14:56 UTCEG score recompute
  19. 2026-10-24 19:31 UTCEG score recompute
  20. 2026-10-24 16:31 UTCEPSS rescoreEPSS 1.7% · 76th percentile
  21. 2026-10-23 18:13 UTCEG score recompute
  22. 2026-10-23 16:31 UTCEPSS rescoreEPSS 1.7% · 76th percentile
  23. 2026-10-22 16:42 UTCEG score recompute
  24. 2026-10-22 16:33 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  25. 2026-10-21 16:31 UTCEPSS rescoreEPSS 0.5% · 39th percentile
Show 45 more
  1. 2026-10-21 15:22 UTCEG score recompute
  2. 2026-10-20 16:31 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  3. 2026-10-20 14:04 UTCEG score recompute
  4. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  5. 2026-10-19 12:45 UTCEG score recompute
  6. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  7. 2026-10-18 05:09 UTCEG score recompute
  8. 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  9. 2026-10-17 09:47 UTCEG score recompute
  10. 2026-10-16 16:40 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  11. 2026-10-16 08:27 UTCEG score recompute
  12. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  13. 2026-10-15 07:09 UTCEG score recompute
  14. 2026-10-14 16:31 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  15. 2026-10-14 03:01 UTCEG score recompute
  16. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  17. 2026-10-12 16:40 UTCEG score recompute
  18. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  19. 2026-10-11 19:53 UTCEG score recompute
  20. 2026-10-11 18:28 UTCEG score recompute
  21. 2026-10-11 15:01 UTCEG score recompute
  22. 2026-10-11 13:47 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  23. 2026-10-11 12:03 UTCEG score recompute
  24. 2026-10-10 20:10 UTCEG score recompute
  25. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  26. 2026-10-09 20:35 UTCEG score recompute
  27. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  28. 2026-10-09 16:40 UTCEG score recompute
  29. 2026-10-08 19:43 UTCEG score recompute
  30. 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  31. 2026-10-08 02:09 UTCEG score recompute
  32. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  33. 2026-10-06 18:47 UTCEG score recompute
  34. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  35. 2026-10-05 21:06 UTCEG score recompute
  36. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  37. 2026-10-05 01:23 UTCEG score recompute
  38. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  39. 2026-10-03 18:02 UTCEG score recompute
  40. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  41. 2026-10-02 22:21 UTCEG score recompute
  42. 2026-10-02 21:23 UTCEG score recompute
  43. 2026-10-02 19:20 UTCEG score recompute
  44. 2026-10-02 19:10 UTCEG score recomputeFirst assessed: 10.0 CRITICAL
  45. 2026-10-02 19:10 UTCMITRE cvelistV5first tracked

Publicly available exploits

(2 references)

Public exploit code is referenced for this CVE (1 GitHub PoC), as is 1 Nuclei detection template. A detection template checks whether a system is affected; it is not necessarily exploit code. Defenders should treat patch urgency accordingly.

  • Nucleihttp/cves/2026/CVE-2026-103956.yaml
    Recorded Oct 22, 2026

    Loom for AWS < 1.6.1 - Unauthenticated Super-Admin Access

    Open source ↗
  • GitHub PoCabraxas/cve-2026-103956-loom-unauth
    Published Oct 3, 2026

    CVE-2026-103956 - Loom for AWS - Critical - Auth bypass - unauthenticated super-admin when no IdP is configured

    Open source ↗

Frequently asked(5)

What is CVE-2026-103956?
CVE-2026-103956 is a critical-severity vulnerability; its CVE record was published on October 2, 2026. Missing authentication for critical function in the authentication dependency in Loom for AWS before 1.6.1 allowed remote actors to obtain super-admin authority over the agent control plane, including registering tool servers, reading stored integration credentials, and rewriting the IAM role…
When was the CVE record for CVE-2026-103956 published?
The CVE record for CVE-2026-103956 was published on October 2, 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 9, 2026; the record at its source may have been updated since.
Is CVE-2026-103956 actively exploited?
CVE-2026-103956 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 2.5% probability of exploitation in the next 30 days (84th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-103956?
CVE-2026-103956 has a CVSS base score of 10.0 (the CNA's own assessment, by amzn; NVD's own analysis pending).
How do I remediate CVE-2026-103956?
A fix for CVE-2026-103956 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-103956 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-103956

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