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NVD / CVE Program· CNA mitre

CVE-2020-21817: A null pointer dereference issue exists in GNU LibreDWG 0.10.2641 via htmlescape ../../programs/escape.c:29.

MediumCVSS 6.5 · v3.1—No exploit No fix recorded

Noroxi assessment

Priority: Monitor (action score 26/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.91% (FIRST EPSS); higher than 60.4% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • According to the record, no fixed version is available yet.

Low priority for now. Update when a fix is released; follow the vendor's advisory.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

A null pointer dereference issue exists in GNU LibreDWG 0.10.2641 via htmlescape ../../programs/escape.c:29. which causes a denial of service (application crash).

Published
May 17, 2021
Updated
Jul 9, 2026
EPSS
0.9% · 60th percentile

Report tools

JSON

Action score

26

Monitor

Low priority for now.

CVSS
26 / 40 · 6.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.9%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • No fixed version yet

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When you'll hear from us

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  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
gnulibredwg

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • gnu libredwg0.10.2641

Same product

gnu: all records

Other highest-scoring records for the same primary product.

  • CVE-2019-20914An issue was discovered in GNU LibreDWG through 0.9.3.
    40Plan
  • CVE-2022-35164LibreDWG v0.12.4.4608 & commit f2dea29 was discovered to contain a heap use-after-free via bit_copy_chain.
    39Monitor
  • CVE-2021-28237LibreDWG v0.12.3 was discovered to contain a heap-buffer overflow via decode_preR13.
    39Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2020-21815May 17, 2021 · A null pointer deference issue exists in GNU LibreDWG 0.10.2641 via output_TEXT ../../programs/dwg2SVG.c:114, which causes a denial of…
    26Monitor
  • ← EarlierCVE-2020-21816May 17, 2021 · A heab based buffer overflow issue exists in GNU LibreDWG 0.10.2641 via htmlescape ../../programs/escape.c:46.
    35Monitor
  • Later →CVE-2020-21818May 17, 2021 · A heap based buffer overflow vulnerability exists in GNU LibreDWG 0.10.2641 via htmlescape ../../programs/escape.c:48.
    35Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-476 · NULL Pointer Dereference

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

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