CVE-2022-4087

Plaintext disclosure via TLS padding oracle

Published Nov 21, 2022 · Updated Apr 15, 2025

Observable discrepancy in iPXE TLS allows remote authenticated users to infer plaintext through crafted CBC ciphertext. In tls_new_ciphertext in src/net/tls.c, invalid block padding returns before MAC computation, while valid padding continues through the MAC path, creating a timing oracle. Exploitation requires access to a TLS exchange using a block cipher and repeated ciphertext probes; the reported consequence is limited to indirect plaintext disclosure.

CVSS severity4.3
Medium
EPSS probability0.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Observable discrepancy in iPXE TLS allows remote authenticated users to infer plaintext through crafted CBC ciphertext. In tls_new_ciphertext in src/net/tls.c, invalid block padding returns before MAC computation, while valid padding continues through the MAC path, creating a timing oracle. Exploitation requires access to a TLS exchange using a block cipher and repeated ciphertext probes; the reported consequence is limited to indirect plaintext disclosure.

The record

CVE
CVE-2022-4087
Published
Nov 21, 2022
Updated
Apr 15, 2025
Vendor
iPXE
Product
iPXE
Classifications
CWE-203, CWE-284
Attack vector
adjacent
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 21, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 15, 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?

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  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesauthenticated

What is affected?

iPXE · iPXEversion=n/a

Published CVSS scores

4.3NISTCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
2.6VulDBCVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:L/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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-203Observable Discrepancy
CWE-284Improper Access Control

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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