CVE-2020-25577Public exploit

Root code execution via unchecked RDNSS option length

Published Mar 29, 2021 · Updated Aug 4, 2024

Buffer overflow in FreeBSD rtsold on affected releases allows remote attackers to execute code as root through a malformed IPv6 advertisement. The rtsol_input function trusts the RDNSS option length while iterating over addresses, causing reads beyond the received packet boundary. Attackers must share the physical link with a listening rtsold instance; FreeBSD 12.2 confines the daemon in Capsicum.

CVSS severity9.8
Critical
EPSS probability1.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Buffer overflow in FreeBSD rtsold on affected releases allows remote attackers to execute code as root through a malformed IPv6 advertisement. The rtsol_input function trusts the RDNSS option length while iterating over addresses, causing reads beyond the received packet boundary. Attackers must share the physical link with a listening rtsold instance; FreeBSD 12.2 confines the daemon in Capsicum.

The record

CVE
CVE-2020-25577
Published
Mar 29, 2021
Updated
Aug 4, 2024
Vendor
The FreeBSD Project
Product
FreeBSD
Classifications
CWE-120, T1210
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 29, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=FreeBSD 12.2-RELEASE before p1, 12.1-RELEASE before p11, 11.4-RELEASE before p5

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

The FreeBSD Project · FreeBSDversion=FreeBSD 12.2-RELEASE before p1, 12.1-RELEASE before p11, 11.4-RELEASE before p5

Published CVSS scores

10.0NIST NVDAV:N/AC:L/Au:N/C:C/I:C/A:C
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1210Exploitation of Remote Services

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo