Reference page — cumulative record through Monday, October 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2023-27537

CVE-2023-27537MEDIUM

n/a https://github.com/curl/curl — A double free vulnerability exists in libcurl <8.0.0 when sharing HSTS data between separate "handles".

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   H   N   N  U  N  N  H    5.9   .0190   79.3     —

AFFECTED
  Product                       Versions          Fixed
  https://github.com/curl/curl  Fixed in 8.0.0 –  —

TIMELINE
  Mar 2   Reserved by hackerone
  Mar 30  Published (CNA: hackerone)
  Oct 14  ENRICHED — CVE-2023-27537 (https://github.com/curl/curl). Received CVSS 5.9 and CPE data from NVD.
  Oct 14  EXPLOIT PUBLISHED — CVE-2023-27537 (https://github.com/curl/curl). Public exploit reference added.

CWE-415 · CNA: hackerone · CVSS v3.1 · 5 references · NVD status: Modified

Description

A double free vulnerability exists in libcurl <8.0.0 when sharing HSTS data between separate "handles". This sharing was introduced without considerations for do this sharing across separate threads but there was no indication of this fact in the documentation. Due to missing mutexes or thread locks, two threads sharing the same HSTS data could end up doing a double-free or use-after-free.

Lifecycle

Complete event history — 4 events, chronological
Date	Event	Detail
March 2, 2023	Reserved	Reserved by hackerone
March 30, 2023	Published	Published (CNA: hackerone)
October 14, 2026	ENRICHED	ENRICHED — CVE-2023-27537 (https://github.com/curl/curl). Received CVSS 5.9 and CPE data from NVD.
October 14, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2023-27537 (https://github.com/curl/curl). Public exploit reference added.

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
n/a	https://github.com/curl/curl	—	Fixed in 8.0.0	—

Weaknesses

CWE-415

References (5)

https://cert-portal.siemens.com/productcert/html/ssa-398330.html
https://cert-portal.siemens.com/productcert/html/ssa-943925.html
https://hackerone.com/reports/1897203 [Exploit, Third Party Advisory]
https://security.gentoo.org/glsa/202310-12 [Third Party Advisory]
https://security.netapp.com/advisory/ntap-20230420-0010/ [Third Party Advisory]

Authoritative record: CVE-2023-27537 at cve.org

Weaknesses: CWE-415

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2023-27537 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Monday, October 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.