CVE-2015-5739

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-14. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 10%CVSS: 9.8Exploit: NoneExposed: 0

A fix is available — apply it.

The net/http library in net/textproto/reader.go in Go before 1.4.3 does not properly parse HTTP header keys, which allows remote attackers to conduct HTTP request smuggling attacks via a space instead of a hyphen, as demonstrated by "Content Length" instead of "Content-Length."

CVSS v3
9.8
EG Score
9.8(medium)
EPSS
95.0%
KEV
Not listed

Published

October 18, 2017

Last Modified

May 13, 2026

Advisory Details (7)

Auto-updated May 16, 2026
Patch available. Sources: redhat.
generic

net/textproto: don't treat spaces as hyphens in header keys · golang/go@117ddcb · GitHub

https://github.com/golang/go/commit/117ddcb83d7f42d6aa72241240af99ded81118e9
redhat Patch Available

1250352 – (CVE-2015-5739, CVE-2015-5740, CVE-2015-5741) CVE-2015-5739 CVE-2015-5740 CVE-2015-5741 golang: HTTP request smuggling in net/http library

https://bugzilla.redhat.com/show_bug.cgi?id=1250352
generic
http://www.securityfocus.com/bid/76281
generic

oss-sec: Re: CVE Request - Go net/http library - HTTP smuggling

http://seclists.org/oss-sec/2015/q3/294
generic

oss-sec: Re: CVE Request - Go net/http library - HTTP smuggling

http://seclists.org/oss-sec/2015/q3/292
generic

oss-sec: CVE Request - Go net/http library - HTTP smuggling

http://seclists.org/oss-sec/2015/q3/237
generic
http://rhn.redhat.com/errata/RHSA-2016-1538.html

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatgolang-0:1.6.3-1.el7_2.12016-08-02redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
Go(1)
PackageVulnerable rangeFixed inDependents
stdlib—1.4.3—

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 11× in last 7d / 40× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 107 total refreshes for this CVE.

  1. 2026-07-22 21:59 UTCEG score recompute
  2. 2026-07-22 14:04 UTCEPSS rescore
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  62. 2026-05-20 07:27 UTCVendor advisory
  63. 2026-05-20 07:27 UTCGHSA enrichment
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  74. 2026-05-19 07:56 UTCVendor advisory
  75. 2026-05-19 07:56 UTCGHSA enrichment

Frequently asked(5)

What is CVE-2015-5739?
CVE-2015-5739 is a critical vulnerability published on October 18, 2017. The net/http library in net/textproto/reader.go in Go before 1.4.3 does not properly parse HTTP header keys, which allows remote attackers to conduct HTTP request smuggling attacks via a space instead of a hyphen, as demonstrated by "Content Length" instead of "Content-Length."
When was CVE-2015-5739 disclosed?
CVE-2015-5739 was first published in the National Vulnerability Database on October 18, 2017, with the most recent update on May 13, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2015-5739 actively exploited?
CVE-2015-5739 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 95.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2015-5739?
CVE-2015-5739 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2015-5739?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2015-5739, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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