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CVE-2019-15703: An Insufficient Entropy in PRNG vulnerability in Fortinet FortiOS 6.2.1, 6.2.0, 6.0.8 and below for device...

An Insufficient Entropy in PRNG vulnerability in Fortinet FortiOS 6.2.1, 6.2.0, 6.0.8 and below for device not enable hardware TRNG token and models not support builtin TRNG seed allows attacker to theoretically recover the long term ECDSA secret in a TLS client with a RSA handshake and mutual ECDSA authentication via the help of flush+reload side channel attacks in FortiGate VM models only.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This FortiOS issue concerns weak randomness on specific FortiGate VM deployments. Under narrow conditions, an attacker could theoretically recover a long-term ECDSA TLS client secret using a side-channel attack. The source bundle does not provide CVSS, confirmed exploitation, or a named fix.

Executive priority

Prioritize targeted assessment rather than broad emergency action. The issue is cryptographically serious if all conditions match, but the provided evidence frames exploitation as theoretical and narrowly scoped to FortiGate VM models.

Technical view

CVE-2019-15703 affects FortiOS 6.2.1, 6.2.0, and 6.0.8 and below on FortiGate VM models only, when hardware TRNG is not enabled and the model lacks builtin TRNG seed support. The described impact is theoretical recovery of a long-term ECDSA secret in a TLS client mutual-authentication scenario.

Likely exposure

Exposure appears limited to FortiGate VM deployments on the listed FortiOS versions with weak or unavailable TRNG seeding and the relevant TLS client authentication use case. Physical appliances or VM models with adequate TRNG support are not identified as affected in the provided sources.

Exploitation context

The source bundle describes a theoretical flush+reload side-channel path. It does not cite public exploitation, KEV listing, weaponized tooling, or observed attacks. Treat exploitation status as unconfirmed.

Researcher notes

Key uncertainties are severity, practical exploitability, and vendor remediation details. Validation should focus on matching all prerequisites from the CVE text before escalating risk. Do not assume appliance impact or active exploitation from the available sources.

Mitigation direction

  • Review Fortinet PSIRT FG-IR-19-186 for vendor-approved fixes or mitigations.
  • Inventory FortiGate VM instances running the listed FortiOS versions.
  • Confirm whether hardware TRNG is enabled or builtin TRNG seed support exists.
  • Reduce exposure of affected TLS mutual-authentication paths where operationally feasible.
  • Plan remediation through Fortinet-supported upgrade or configuration guidance.

Validation and detection

  • Identify FortiGate VM model and FortiOS version for each deployment.
  • Check whether the deployment has hardware TRNG enabled.
  • Confirm whether the VM model supports builtin TRNG seed support.
  • Review TLS client mutual ECDSA authentication usage in affected environments.
  • Document whether each instance matches all affected-condition criteria.
Prepared
Confidence
medium
Sources
3

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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description · low confidence lookup

Credential and access behavior lookup

The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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cve · low confidence lookup

CVE-2019-15703 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
2Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
FortinetFortinet FortiOS6.2.1, 6.2.0, 6.0.8 and belowListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.