CVE-2023-45236Network attack vector

Session hijacking via predictable TCP sequence numbers

Published Jan 16, 2024 · Updated Nov 4, 2025

Predictable TCP sequence numbers in TianoCore EDK II edk2-stable202308 allow remote attackers to hijack NetworkPkg TCP sessions. TcpDxe derives initial sequence numbers without a secret, connection-specific cryptographic hash, making another connection's ISN guessable. Exposure requires PXE or HTTP boot on an untrusted network; successful prediction permits unauthorized session access and confidentiality loss.

CVSS severity5.8
Medium
EPSS probability0.99%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Predictable TCP sequence numbers in TianoCore EDK II edk2-stable202308 allow remote attackers to hijack NetworkPkg TCP sessions. TcpDxe derives initial sequence numbers without a secret, connection-specific cryptographic hash, making another connection's ISN guessable. Exposure requires PXE or HTTP boot on an untrusted network; successful prediction permits unauthorized session access and confidentiality loss.

The record

CVE
CVE-2023-45236
Published
Jan 16, 2024
Updated
Nov 4, 2025
Vendor
TianoCore
Product
EDK II
Classifications
CWE-338, CWE-200, CAPEC-13
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 16, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 4, 2025Record 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=edk2-stable202308

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

TianoCore · EDK IIversion=edk2-stable202308

Published CVSS scores

5.8TianoCoreCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N
7.5NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-338Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)
CWE-200Exposure of Sensitive Information to an Unauthorized Actor
CAPEC-13Subverting Environment Variable Values

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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