9.1Critical

CVE-2026-8927env-set cross-proxy Digest auth state leak

curl curl Published: 2026-07-03 09:16 (4 months ago)

Description

When reusing a libcurl handle for sequential transfers driven by environment-variable proxy configuration, libcurl fails to clear the proxy authentication state between requests. Specifically, if the initial transfer authenticates against `proxyA` using Digest auth, a subsequent transfer routed through `proxyB` erroneously leaks the `Proxy-Authorization:` header intended solely for `proxyA`.

Weakness (CWE): CWE-294

Data: CVE.org, NVD, CISA KEV, FIRST EPSS, Ubuntu. Published as the sources state it, in English.

Affected products and versions

Vendor	Product	Versions
curl	curl	7.12.0 – < 8.14.2, 8.15.0 – < 8.16.1, 8.17.0 – < 8.20.1
haxx	curl	7.12.0 – < 8.21.0

References and patches

https://curl.se/docs/CVE-2026-8927.json Vendor Advisory
https://curl.se/docs/CVE-2026-8927.html PatchVendor Advisory
https://hackerone.com/reports/3744543 ExploitIssue TrackingThird Party Advisory

CPE matches (NVD) (1)

cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:* ≥ 7.12.0 < 8.21.0

CVSS score

9.1Critical

Source: CISA-ADP · CVSS 3.1

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

All scores (2)

CISA-ADP	CVSS 3.1	9.1Critical
134c704f-9b21-4f2e-91b3-4a467353bcc0	CVSS 3.1	9.1Critical

EPSS (chance of exploitation in 30 days)

0.50%

higher than 43% of all CVEs

CISA assessment (SSVC)

Exploitation: poc
Automatable: no
Technical impact: total

Timeline

ID reserved2026-05-19
Published2026-07-03 09:16
Reached IP-DB2026-10-24 23:40
Last updated2026-09-15 10:16

Assigned by (CNA): curl
NVD status: Modified

View at source: CVE.org · NVD

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