CVE-2023-41337

HTTPS request disclosure via cross-context TLS resumption

Published Dec 12, 2023 · Updated Aug 2, 2024

TLS session misdirection in h2o 2.3.0-beta2 and earlier allows attackers to read HTTPS requests via resumed connections. The session ticket code accepts resumption across listener contexts because tickets are not bound to the address, port, or X.509 certificate. Exploitation requires host-level listen directives, backends controlled by multiple entities, an attacker-controlled backend, and packet observation or injection.

CVSS severity6.1
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

TLS session misdirection in h2o 2.3.0-beta2 and earlier allows attackers to read HTTPS requests via resumed connections. The session ticket code accepts resumption across listener contexts because tickets are not bound to the address, port, or X.509 certificate. Exploitation requires host-level listen directives, backends controlled by multiple entities, an attacker-controlled backend, and packet observation or injection.

The record

CVE
CVE-2023-41337
Published
Dec 12, 2023
Updated
Aug 2, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-347, T1557
Attack vector
adjacent
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 12, 2023CVE publishedPublication date reported by the CVE source.
  2. Aug 2, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.1GitHub, Inc.CVSS:3.1/AV:A/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:N
6.7NIST NVDCVSS:3.1/AV:A/AC:L/PR:L/UI:R/S:U/C:H/I:H/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)
Vectoradjacent
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
T1557Adversary-in-the-Middle

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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