CVE-2020-36516Public exploitNetwork attack vector

TCP data injection via manipulable IPID policy

Published Feb 26, 2022 · Updated Aug 4, 2024

TCP session hijacking in Linux kernel 5.16.11 and earlier allows remote attackers to inject forged data or terminate TCP connections. The mixed assignment path clears DF after a forged ICMP Fragmentation Needed message, switches TCP replies to shared hash-based IPID counters, and exposes a collision side channel. Exploitation requires an off-path attacker to find a colliding counter and infer the connection sequence state; success permits forged stream data or a connection reset.

CVSS severity5.9
Medium
EPSS probability0.67%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

TCP session hijacking in Linux kernel 5.16.11 and earlier allows remote attackers to inject forged data or terminate TCP connections. The mixed assignment path clears DF after a forged ICMP Fragmentation Needed message, switches TCP replies to shared hash-based IPID counters, and exposes a collision side channel. Exploitation requires an off-path attacker to find a colliding counter and infer the connection sequence state; success permits forged stream data or a connection reset.

The record

CVE
CVE-2020-36516
Published
Feb 26, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-327, T1565.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 26, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.9NIST NVDAV:N/AC:M/Au:S/C:N/I:P/A:P
5.9NIST NVDCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:L

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-327Use of a Broken or Risky Cryptographic Algorithm
T1565.002Transmitted Data Manipulation

Public exploit references

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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