Skip to main content

curl / libcurl CVE-2026-8458

| EUVDEUVD-2026-41504 MEDIUM
6.5
CVSS 3.1 · Vendor
Share

Severity by source

Vendor (CNA) PRIMARY
6.5 MEDIUM
AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
vuln.today AI
4.8 MEDIUM

Network vector as curl operates over network; AC:H because wrong-reuse requires specific multi-service session conditions; C:L/I:L for potential context bleed, no availability impact.

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
4.0 AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
SUSE
4.2 MEDIUM
AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N
Red Hat
8.1 HIGH
qualitative

Primary rating from Vendor (CNA).

CVSS VectorVendor

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

Lifecycle Timeline

2
CVSS changed
Jul 06, 2026 - 18:22 NVD
6.5 (MEDIUM)
Analysis Generated
Jun 24, 2026 - 18:28 vuln.today

Description PRE-NVD

Disclosed via oss-security. NVD scoring and full description are pending.

AnalysisAI

Wrong connection reuse across different services in curl/libcurl up to 8.20.0 allows curl's connection pool to incorrectly match and reuse an existing connection when the target service differs from the one originally used to establish that connection. This is part of a coordinated batch of 19 CVEs fixed in curl 8.21.0, released June 24, 2026. No public exploit or active exploitation has been identified; the curl project rates this LOW severity, consistent with limited real-world attack surface requiring specific multi-service usage patterns.

Technical ContextAI

curl maintains an internal connection pool (multi-handle connection cache) to reuse established TCP/TLS connections for subsequent transfers to the same host, improving performance. CVE-2026-8458 represents a logic flaw in the connection pool matching algorithm: when an application issues requests to different services - distinguished by protocol, port, or service type - curl incorrectly identifies a pooled connection established for one service as eligible for reuse by a transfer targeting a different service. Related sibling CVEs in the same release (CVE-2026-8286 for wrong STARTTLS reuse, CVE-2026-8932 for incomplete mTLS config matching in conn reuse) confirm a pattern of curl connection-cache selection bugs in the 8.17-8.20 era. The likely CWE class is CWE-706 (Use of Incorrectly-Resolved Name or Reference) or closely related state-management defects in pool key comparison. The flaw affects libcurl consumers; command-line tool impact depends on multi-transfer usage patterns.

RemediationAI

Upgrade curl and libcurl to version 8.21.0, released June 24, 2026, which resolves CVE-2026-8458 alongside 18 other security issues patched in the same coordinated release. The curl project advisory at https://curl.se/docs/CVE-2026-8458.html and the oss-security announcement at https://seclists.org/oss-sec/2026/q2/1012 are the authoritative references. For applications that cannot immediately upgrade, a compensating control is to avoid connection pool reuse across different service types by using separate easy handles or resetting the multi-handle session between transfers to distinct services - this eliminates the incorrect reuse condition at the cost of losing connection-reuse performance benefits. Applying the upstream patch and rebuilding libcurl from source is also viable if a packaged 8.21.0 is not yet available for the target platform.

More in Curl

View all
CVE-2013-0249 HIGH POC
7.5 Mar 08

Stack-based buffer overflow in the Curl_sasl_create_digest_md5_message function in lib/curl_sasl.c in curl and libcurl 7

CVE-2015-3145 HIGH
7.5 Apr 24

The sanitize_cookie_path function in cURL and libcurl 7.31.0 through 7.41.0 does not properly calculate an index, which

CVE-2022-32221 CRITICAL POC
9.8 Dec 05

When doing HTTP(S) transfers, libcurl might erroneously use the read callback (`CURLOPT_READFUNCTION`) to ask for data t

CVE-2022-32207 CRITICAL POC
9.8 Jul 07

When curl < 7.84.0 saves cookies, alt-svc and hsts data to local files, it makes the operation atomic by finalizing the

CVE-2018-0500 CRITICAL POC
9.8 Jul 11

Curl_smtp_escape_eob in lib/smtp.c in curl 7.54.1 to and including curl 7.60.0 has a heap-based buffer overflow that mig

CVE-2023-23914 CRITICAL POC
9.1 Feb 23

A cleartext transmission of sensitive information vulnerability exists in curl <v7.88.0 that could cause HSTS functional

CVE-2023-27534 HIGH POC
8.8 Mar 30

A path traversal vulnerability exists in curl <8.0.0 SFTP implementation causes the tilde (~) character to be wrongly re

CVE-2023-27533 HIGH POC
8.8 Mar 30

A vulnerability in input validation exists in curl <8.0 during communication using the TELNET protocol may allow an atta

CVE-2025-0665 HIGH POC
7.0 Feb 05

A double-close vulnerability exists in libcurl when tearing down connection channels after threaded name resolution, cau

CVE-2022-27778 HIGH POC
8.1 Jun 02

A use of incorrectly resolved name vulnerability fixed in 7.83.1 might remove the wrong file when `--no-clobber` is used

CVE-2021-22901 HIGH POC
8.1 Jun 11

curl 7.75.0 through 7.76.1 suffers from a use-after-free vulnerability resulting in already freed memory being used when

CVE-2020-8177 HIGH POC
7.8 Dec 14

curl 7.20.0 through 7.70.0 is vulnerable to improper restriction of names for files and other resources that can lead to

Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SLES15-SP5-CHOST-BYOS-SAP-CCloud Affected
SLES15-SP6-CHOST-BYOS Affected
SLES15-SP6-CHOST-BYOS-Aliyun Affected
SLES15-SP6-CHOST-BYOS-Azure Affected
SLES15-SP6-CHOST-BYOS-EC2 Affected

Share

CVE-2026-8458 vulnerability details – vuln.today

This site uses cookies essential for authentication and security. No tracking or analytics cookies are used. Privacy Policy