CVE-2021-43767Network attack vector

Query-result manipulation via buffered pre-TLS data

Published Aug 25, 2022 · Updated Aug 4, 2024

TLS response injection in Yandex Odyssey 1.1 allows man-in-the-middle attackers to alter initial PostgreSQL query results. The backend TLS negotiation path accepts unread bytes buffered after the server's SSL-accept response and later forwards them as trusted server data. Exploitation requires storage configured for trust authentication with clientcert or cert authentication, and the bounded consequence is false responses to the client's first few queries.

CVSS severity5.9
Medium
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

TLS response injection in Yandex Odyssey 1.1 allows man-in-the-middle attackers to alter initial PostgreSQL query results. The backend TLS negotiation path accepts unread bytes buffered after the server's SSL-accept response and later forwards them as trusted server data. Exploitation requires storage configured for trust authentication with clientcert or cert authentication, and the bounded consequence is false responses to the client's first few queries.

The record

CVE
CVE-2021-43767
Published
Aug 25, 2022
Updated
Aug 4, 2024
Vendor
Yandex
Product
Odyssey
Classifications
CWE-522, CWE-295, T1557, T1565.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 25, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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=Odyssey 1.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Yandex · Odysseyversion=Odyssey 1.1

Published CVSS scores

5.9NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/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.

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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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-522Insufficiently Protected Credentials
CWE-295Improper Certificate Validation
T1557Adversary-in-the-Middle
T1565.002Transmitted Data Manipulation

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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