CVE-2020-36420Public exploitNetwork attack vector

Proxy crash via malformed Range header assertion

Published Jul 14, 2021 · Updated Aug 4, 2024

Reachable assertion in Polipo 1.1.1 and earlier allows remote attackers to crash the proxy via a malformed HTTP Range header. Range parsing in server.c accepts an inverted byte range such as bytes=3-2 and evaluates an assertion requiring the ending offset to exceed the starting offset, terminating the process. The crash requires a build compiled without NDEBUG and interrupts service for all clients of the affected, no-longer-maintained proxy.

CVSS severity7.5
High
EPSS probability1.90%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reachable assertion in Polipo 1.1.1 and earlier allows remote attackers to crash the proxy via a malformed HTTP Range header. Range parsing in server.c accepts an inverted byte range such as bytes=3-2 and evaluates an assertion requiring the ending offset to exceed the starting offset, terminating the process. The crash requires a build compiled without NDEBUG and interrupts service for all clients of the affected, no-longer-maintained proxy.

The record

CVE
CVE-2020-36420
Published
Jul 14, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-617, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 14, 2021CVE 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

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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 exploitPublished

Weakness, pattern, technique

CWE-617Reachable Assertion
T1499.004Endpoint Denial of Service: Application or System Exploitation

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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