CVE-2017-16876

Cross-site scripting (XSS) vulnerability in the _keyify function in mistune.py in Mistune before 0.8.1 allows remote attackers to inject arbitrary web script or HTML by leveraging failure to escape the "key" argument.

Published: 2017-12-29 Last update: 2026-05-13 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2017-16876 is rated Moderate Risk (54.4/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 2.20%). EPSS rose +1.97% over the last day, indicating growing attacker interest. Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2017-16876

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.23% 2.20% +1.97%
2 2026-04-05 0.58% 0.23% -0.35%
3 2025-03-30 — 0.58% —

Full EPSS history (10 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2017-16876

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.1 3.0 MEDIUM
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 2.7 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2017-16876

GitHub Security Advisory for CVE-2017-16876

GHSA-98gj-wwxm-cj3h · Severity: medium · Ecosystem: pip — mistune Cross-site scripting (XSS) vulnerability

OS Trackers for CVE-2017-16876

vendor priority summary link
debian not yet assigned CVE-2017-16876 not yet assigned priority: Debian including 1 source packages (mistune), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2017-16876
ubuntu medium CVE-2017-16876 medium priority: Ubuntu including 1 source packages (mistune), 21 status rows across 21 suites (artful, bionic, cosmic, disco, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial, zesty): not-affected 16, ignored 2, DNE 1, needed 1, released 1. https://ubuntu.com/security/CVE-2017-16876

Affected software / configurations for CVE-2017-16876

Vendor Product Version Raw CPE
mistune_project mistune < 0.8.1 cpe:2.3:a:mistune_project:mistune:*:*:*:*:*:*:*:*
fedoraproject fedora 26 cpe:2.3:o:fedoraproject:fedora:26:*:*:*:*:*:*:*

References for CVE-2017-16876

cvelogic Threat Intelligence