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No exploitation reported

CVE-2017-1000257

No exploitation reported by the sources we read.

  • Published2017-10-31
  • WeaknessCWE-119

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

An IMAP FETCH response line indicates the size of the returned data, in number of bytes. When that response says the data is zero bytes, libcurl would pass on that (non-existing) data with a pointer and the size (zero) to the deliver-data function. libcurl's deliver-data function treats zero as a magic number and invokes strlen() on the data to figure out the length. The strlen() is called on a heap based buffer that might not be zero terminated so libcurl might read beyond the end of it into whatever memory lies after (or just crash) and then deliver that to the application as if it was actually downloaded.

Timeline

dates in UTC
  1. 2017-10-3121:29CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2017-1000257?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2017-1000257?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Debian debian linux
BranchAffectedFixed in
8.0= 8.0no fix published
9.0= 9.0no fix published
Haxx libcurl
BranchAffectedFixed in
7.x≥ 7.20.0, ≤ 7.56.0no fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • CISA-ADPSSVC decisionnone2026-04-15
  • OpenCVESSVC decisionnone—
  • CISA-ADPCVSS 3.19.12026-04-15
  • NVDCVSS 3.09.1read 2026-10-23
  • NVDCVSS 2.06.4read 2026-10-23
  • CISA-ADPweakness (CWE)CWE-1192026-04-15
  • NVDweakness (CWE)CWE-119read 2026-10-23
  • FIRST EPSSEPSS score6.2 %2026-10-22

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Published
2017-10-31
Last Modified
2026-06-17
NVD status
Modified

Frequently asked questions

What is CVE-2017-1000257?

An IMAP FETCH response line indicates the size of the returned data, in number of bytes. When that response says the data is zero bytes, libcurl would pass on that (non-existing) data with a pointer and the size (zero) to the deliver-data function. libcurl's deliver-data function treats zero as a magic number and invokes strlen() on the data to figure out the length. The strlen() is called on a heap based buffer that might not be zero terminated so libcurl might read beyond the end of it into whatever memory lies after (or just crash) and then deliver that to the application as if it was actually downloaded.

Is CVE-2017-1000257 actively exploited?

Active exploitation of CVE-2017-1000257 has not been confirmed. Its EPSS score was 6.2% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2017-1000257?

CVE-2017-1000257 has a CVSS v3 base score of 9.1 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H.

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