CVE-2021-3047Network attack vector

Administrator session impersonation via weak authentication PRNG

Published Aug 11, 2021 · Updated Sep 17, 2024

Weak randomness in PAN-OS web authentication allows remote authenticated users to impersonate another interface administrator. The web interface uses a cryptographically weak pseudorandom number generator while issuing authentication secrets, making administrator sessions predictable from repeated observations. Exploitation requires an authenticated account and observation of that account's secrets over a long period; every web authentication method is exposed.

CVSS severity4.2
Medium
EPSS probability0.45%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Weak randomness in PAN-OS web authentication allows remote authenticated users to impersonate another interface administrator. The web interface uses a cryptographically weak pseudorandom number generator while issuing authentication secrets, making administrator sessions predictable from repeated observations. Exploitation requires an authenticated account and observation of that account's secrets over a long period; every web authentication method is exposed.

The record

CVE
CVE-2021-3047
Published
Aug 11, 2021
Updated
Sep 17, 2024
Vendor
Palo Alto Networks
Product
PAN-OS
Classifications
CWE-338, T1550.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 11, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.0 <10.0.4 changes=[{"at":"10.0.4","status":"unaffected"}]
  2. Affected versionversion=8.1 <8.1.19 changes=[{"at":"8.1.19","status":"unaffected"}]
  3. Affected versionversion=9.0 <9.0.14 changes=[{"at":"9.0.14","status":"unaffected"}]
  4. Affected versionversion=9.1 <9.1.10 changes=[{"at":"9.1.10","status":"unaffected"}]

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Palo Alto Networks · PAN-OSversion=10.0 <10.0.4 changes=[{"at":"10.0.4","status":"unaffected"}]; version=8.1 <8.1.19 changes=[{"at":"8.1.19","status":"unaffected"}]; version=9.0 <9.0.14 changes=[{"at":"9.0.14","status":"unaffected"}]; version=9.1 <9.1.10 changes=[{"at":"9.1.10","status":"unaffected"}]

Published CVSS scores

4.2Palo Alto NetworksCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-338Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)
T1550.004Use Alternate Authentication Material: Web Session Cookie

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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