What’s Vulnerable › Vulnerabilities

CVE-2018-20721

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2019-01-16 · updated 2026-06-17
• Weakness: CWE-125

Description

URI_FUNC() in UriParse.c in uriparser before 0.9.1 has an out-of-bounds read (in uriParse*Ex* functions) for an incomplete URI with an IPv6 address containing an embedded IPv4 address, such as a "//[::44.1" address.

Affected products

• Debian Linux: 8.0, 9.0
• uriparser: before 0.9.1 — fixed in 0.9.1

How to fix

Upgrade to a fixed version: uriparser 0.9.1. Check the vendor advisory for mitigations.

References

• https://github.com/uriparser/uriparser/blob/master/ChangeLog
• https://github.com/uriparser/uriparser/commit/cef25028de5ff872c2e1f0a6c562eb3ea9ecbce4
• https://lists.debian.org/debian-lts-announce/2019/02/msg00028.html
• https://lists.debian.org/debian-lts-announce/2021/11/msg00029.html
• https://github.com/uriparser/uriparser/blob/master/ChangeLog
• https://github.com/uriparser/uriparser/commit/cef25028de5ff872c2e1f0a6c562eb3ea9ecbce4
• https://lists.debian.org/debian-lts-announce/2019/02/msg00028.html
• https://lists.debian.org/debian-lts-announce/2021/11/msg00029.html

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