CVE-2020-13111Network attack vector

Unauthenticated server crash via negative chunk length

Published May 16, 2020 · Updated Aug 4, 2024

Out-of-bounds write in NaviServer 4.99.4 through 4.99.19 allows remote attackers to crash the server via a chunked HTTP request. ChunkedDecode in nsd/driver.c accepts a negative chunk length and passes that value as memmove's unsigned size, producing an invalid memory move. An unauthenticated network request using chunked transfer encoding is sufficient to interrupt the NaviServer process; no confidentiality or integrity effect is reported.

CVSS severity7.5
High
EPSS probability1.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in NaviServer 4.99.4 through 4.99.19 allows remote attackers to crash the server via a chunked HTTP request. ChunkedDecode in nsd/driver.c accepts a negative chunk length and passes that value as memmove's unsigned size, producing an invalid memory move. An unauthenticated network request using chunked transfer encoding is sufficient to interrupt the NaviServer process; no confidentiality or integrity effect is reported.

The record

CVE
CVE-2020-13111
Published
May 16, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-20, CWE-787, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 16, 2020CVE 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

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
CWE-787Out-of-bounds Write
T1499Endpoint Denial of Service

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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