CVE-2020-35636: A code execution vulnerability exists in the Nef polygon-parsing functionality of CGAL libcgal CGAL-5.1.1 in N

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CRITICAL 9.8REMOTEWATCHLISTDOWNGRADEMITIGATE

CVE-2020-35636 is a critical-severity flaw (CVSS 9.8) affecting computational geometry algorithms library, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A code execution vulnerability exists in the Nef polygon-parsing functionality of CGAL libcgal CGAL-5.1.1 in Nef_S2/SNC_io_parser.h SNC_io_parser::read_sface() sfh->volume() OOB read. A specially crafted malformed file can lead to an out-of-bounds read and type confusion, which could lead to code execution. An attacker can provide malicious input to trigger this vulnerability.

Why this priority

Critical severity
Public exploit reference
Remotely exploitable, no login, no user action
On your watchlist

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	3.3% (top 12%)
CISA exploited list	No
Weakness	CWE-129, CWE-125, CWE-843
Published	2021-03-04
Last modified	2026-06-17

Publisher (CNA): Talos · Vendor: cgal · debian

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-03-04 20:15 UTCPublished CVE record published
2026-06-17 03:14 UTCUpdated Record last modified

cgal computational geometry algorithms library DOWNGRADE

Affected: 5.1.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.1.1

1. Check installed version

apt-cache policy computational-geometry-algorithms-library || rpm -q computational-geometry-algorithms-library || computational-geometry-algorithms-library --version

2. No fixed release: DOWNGRADE to a release before 5.1.1 (Debian / Ubuntu)

apt-cache madison computational-geometry-algorithms-library sudo apt install computational-geometry-algorithms-library=<VERSION_BEFORE_5.1.1> sudo apt-mark hold computational-geometry-algorithms-library

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list computational-geometry-algorithms-library sudo dnf downgrade computational-geometry-algorithms-library-<VERSION_BEFORE_5.1.1> sudo dnf versionlock add computational-geometry-algorithms-library

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

debian debian linux MITIGATE

Affected: 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 10.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-35636?

computational geometry algorithms library: downgrade or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-35636 being exploited?

CVE-2020-35636 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-35636 affect?

CVE-2020-35636 affects computational geometry algorithms library, debian linux. Severity is critical (CVSS 9.8). A code execution vulnerability exists in the Nef polygon-parsing functionality of CGAL libcgal CGAL-5.1.1 in Nef_S2/SNC_io_parser.h SNC_io_parser::read_sface() sfh->volume() OOB read. A specially crafted malformed file can lead to an out-of

How urgent is CVE-2020-35636?

Priority 71/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities

Related CVEs

CVE-2020-35635 HIGH 8.8 DOWNGRADE MITIGATE A code execution vulnerability exists in the Nef polygon-parsing functionality of CGAL libcgal CGAL-5.1.1 in N
CVE-2020-35634 HIGH 8.8 DOWNGRADE MITIGATE A code execution vulnerability exists in the Nef polygon-parsing functionality of CGAL libcgal CGAL-5.1.1
CVE-2020-35633 HIGH 8.8 DOWNGRADE MITIGATE A code execution vulnerability exists in the Nef polygon-parsing functionality of CGAL libcgal CGAL-5.1.1
CVE-2020-35632 HIGH 8.8 DOWNGRADE MITIGATE Multiple code execution vulnerabilities exists in the Nef polygon-parsing functionality of CGAL libcgal CGAL-5
CVE-2020-35631 HIGH 8.8 DOWNGRADE MITIGATE Multiple code execution vulnerabilities exists in the Nef polygon-parsing functionality of CGAL libcgal CGAL-5

References

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