CVE-2021-3517
No source can show you its own past. This one can.
Print this page to keep the view as it stands on this date. Everything hidden behind a disclosure opens, and every receipt prints with its value.
There is a flaw in the xml entity encoding functionality of libxml2 in versions before 2.9.11
rank 36 = 4 + 22 + 1 + 9 + 0
rank@v1 · scheduled
Someone is already using it
CISA KEV catalog · public proof-of-concept · FIRST EPSS
EPSS 0.16986 · without this subject the record ranks 32
What it costs you if it fires
NVD CVSS base score, then the CNA's own
CVSS 8.6, from NVD · without this subject the record ranks 14
It is getting worse, not staying still
FIRST EPSS series, rescorings and bad loads removed
rose on 2026-09-28 · without this subject the record ranks 35
How much of the world it touches
NVD CPE configurations
15 products in the CPE ranges · without this subject the record ranks 27
Someone else already set the date
CISA KEV remediation due date
no CISA due date · without this subject the record ranks 36
$678,000 = $4.99M incident cost x 0.8004932139359172 exposure x 0.16986 likelihood
udv@v1 · unaudited · wrong for you until you say what you run
$4.99M is the cost of a breach that happened, from IBM Cost of a Data Breach Report 2026, global average. It is not the value of any asset of yours. That average already covers breaches of every severity, so scaling it by exposure understates a partial-impact record. That is an assumption, not a measurement. Your own asset value goes in the decision record.
Hindsight · the state
Foresight · where to check next
This record is one instance of CWE-787, out-of-bounds write. The index holds 14893 prior instances of this class, 164 KEV-listed. The nearest of its KEV-listed records are drawn beside this. taxonomy@v1
Running libxml2? Check your version
A deterministic range check against the ranges this record publishes. It tells you where a version sits in the record, not whether your deployment is exploitable. No account needed.
Watch this record
Matches your own product list against every record this index holds, and tells you when one of them moves.
Set up a watchlist (free with an account: one stack of five products)
Record your call
Keep your verdict, your reason and the evidence together. The record takes its date when you save it.
AcceptDeferPatch by…Not affectedMitigatedChoose your verdict, then sign in or use an email link. Your first 100 records are free. Evidence is frozen when the record is created.
Private to your organization unless you share it. Put the proof link in your ticket so a reviewer can inspect the basis for your call. See how decision records work.
Harm, if it fires from the vector and the weakness
Written for the ticket you're about to file.
CISA KEV & Federal Remediation Deadline from the record and CISA
The fix, and how long it's been waiting.
Exploit Status & Known PoCs a ladder, not a score
Current rung: Nothing observed in held sources.
- RUNG 1Nothing observed in held sources
- RUNG 2Proof-of-concept published
- RUNG 3Exploited in the wild · CISA KEV listed
- RUNG 4Ransomware campaign use known
Affected & Fixed Versions as published
Show all 15 published ranges
A rung lights from a row in the index, never from an assessment. "Held sources" is the true scope of the claim: this index reads the CVE record, NVD, CISA KEV, FIRST's EPSS and public proof-of-concept repositories, and it does not observe attacks.
What it is stated by the CNA
There is a flaw in the xml entity encoding functionality of libxml2 in versions before 2.9.11. An attacker who is able to supply a crafted file to be processed by an application linked with the affected functionality of libxml2 could trigger an out-of-bounds read. The most likely impact of this flaw is to application availability, with some potential impact to confidentiality and integrity if an attacker is able to use memory information to further exploit the application. receipt
NVD's analysis a second authority
- severity
- 8.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
- weakness
- CWE-787; CWE-125
- affected versions
- xmlsoft libxml2 < 2.9.11; redhat enterprise linux 8.0; fedoraproject fedora 33; and 12 more, listed in full below
- also scored by
- 8.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
check it yourself lists.fedoraproject.org lists.debian.org bugzilla.redhat.com lists.fedoraproject.org lists.apache.org lists.apache.org +7 morereceipt
Dated events
Movement the material steps
Show all 48 observations
48 observations held. A highlighted step crossed a promotion threshold. A step marked with a scoring model moved because the instrument was replaced, not because the vulnerability changed. receipt
The full biography
The record had been public for 5 years, 4 months when this index was last written.
The pattern, elsewhere
This record is one instance of CWE-787, out-of-bounds write. The index holds 14893 prior instances of this class, 164 KEV-listed. The nearest of its KEV-listed records are drawn beside this. [email protected]
"Matches n of m" counts the attributes the two records can both be compared on: the CVSS metrics they share a version of, any weakness class beyond this one, and the vendor. fit-rules@v1
14893 records in this class held. The six above are drawn from the ones CISA has listed as exploited, ranked by how much of the record matches this one. That is why every one of them is KEV-listed: the pool is, so the colour on those spokes says nothing the pool has not already said.
No curated product neighbourhood is held for this product, so the records above are the nearest this index can name. The neighbourhood table covers a small set of products and is extended by hand.
Siblings and hubs
Records related to this one
Browse the index from here
These are index-wide views, not findings about CVE-2021-3517.
What usually comes next
Everything above needs no account. What is below is work: assembling it, scoping it to your estate, watching it, and handing it to someone else.