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Vulnerabilities

Vulnerability · CVE-2019-18277

A flaw was found in HAProxy before 2.0.6.

Published Oct 23, 2019 · catalog updated Jun 17, 2026 · A flaw was found

Last checked Nov 5, 2026. A connected source was read within the last 7 days.

Check this week

CVE-2019-18277 is not in CISA KEV. FIRST estimates a 10.07% chance of exploitation in the next 30 days. Check whether you run A flaw was found.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (A flaw was found).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
10.07%
Remediation
Version ranges on file
Affected products
cpe haproxy/haproxy

A flaw was found in HAProxy before 2.0.6. In legacy mode, messages featuring a transfer-encoding header missing the "chunked" value were not being correctly rejected. The impact was limited but if combined with the "http-reuse always" setting, it could be used to help construct an HTTP request smuggling attack against a vulnerable component employing a lenient parser that would ignore the content-length header as soon as it saw a transfer-encoding one (even if not entirely valid according to the specification).

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe haproxy/haproxy< 2.0.6

How to fix CVE-2019-18277

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2019-18277 is not in CISA KEV. FIRST estimates a 10.07% chance of exploitation in the next 30 days. Check whether you run A flaw was found.

Which versions are affected?

Compare what you have installed with < 2.0.6. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-444: HTTP Request Smuggling. EPSS 10.07%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

HAProxy security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 23, 2019 · Monitored products — high

    Detected

    A flaw was found in HAProxy before 2.0.6. In legacy mode, messages featuring a transfer-encoding header missing the "chunked" value were not being correctly rejected. The impact was limited but if combined with the "http-reuse always" setting, it could be used to help construct an HTTP request smuggling attack against a vulnerable component employing a lenient parser that would ignore the content-

  2. Jun 17, 2026 · Monitored products — high

    Updated

    A flaw was found in HAProxy before 2.0.6. In legacy mode, messages featuring a transfer-encoding header missing the "chunked" value were not being correctly rejected. The impact was limited but if combined with the "http-reuse always" setting, it could be used to help construct an HTTP request smuggling attack against a vulnerable component employing a lenient parser that would ignore the content-

Sources

  • CVE.orgVulnerability recordCVE-2019-18277

    Official CVE identifier

    cve.org
  • Monitored products — highVendor advisoryCVE-2019-18277

    A flaw was found in HAProxy before 2.0.6. In legacy mode, messages featuring a transfer-encoding header missing the "chunked" value were not being correctly rejected. The impact was limited but if combined with the "http-reuse always" setting, it could be used to help construct an HTTP request smuggling attack against a vulnerable component employing a lenient parser that would ignore the content-

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 5, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • CVE.orgNov 4, 2026
  • Monitored products — highNov 2, 2026