CVE-2020-28473Public exploitNetwork attack vector

Cache poisoning via semicolon query splitting

Published Jan 18, 2021 · Updated Sep 16, 2024

Web cache poisoning in Bottle before 0.12.19 allows remote attackers to cache malicious responses via semicolon-cloaked query parameters. Bottle's _parse_qsl function rewrites semicolons as ampersands before splitting the query, while a default proxy omits the cloaked value from its cache key. Exploitation requires a caching proxy with this interpretation mismatch; a poisoned entry can serve attacker-controlled content to later requests.

CVSS severity6.1
Medium
EPSS probability1.76%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Web cache poisoning in Bottle before 0.12.19 allows remote attackers to cache malicious responses via semicolon-cloaked query parameters. Bottle's _parse_qsl function rewrites semicolons as ampersands before splitting the query, while a default proxy omits the cloaked value from its cache key. Exploitation requires a caching proxy with this interpretation mismatch; a poisoned entry can serve attacker-controlled content to later requests.

The record

CVE
CVE-2020-28473
Published
Jan 18, 2021
Updated
Sep 16, 2024
Vendor
BottlePy
Product
Bottle
Classifications
CWE-444, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 18, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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=0 <unspecified
  2. Affected versionversion=unspecified <0.12.19

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

BottlePy · Bottleversion=0 <unspecified; version=unspecified <0.12.19

Published CVSS scores

6.1GitHub Advisory DatabaseCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:H/SC:N/SI:N/SA: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 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-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
T1190Exploit Public-Facing Application

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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