CVE-2021-21707
No source can show you its own past. This one can.
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Special characters break path parsing in XML functions
rank 38 = 19 + 13 + 0 + 6 + 0
rank@v1 · scheduled
Someone is already using it
CISA KEV catalog · public proof-of-concept · FIRST EPSS
EPSS 0.25951 · without this subject the record ranks 19
What it costs you if it fires
NVD CVSS base score, then the CNA's own
CVSS 5.3, from NVD · without this subject the record ranks 25
It is getting worse, not staying still
FIRST EPSS series, rescorings and bad loads removed
no persisting rise in 365 days · without this subject the record ranks 38
How much of the world it touches
NVD CPE configurations
6 products in the CPE ranges · without this subject the record ranks 32
Someone else already set the date
CISA KEV remediation due date
no CISA due date · without this subject the record ranks 38
$311,000 = $4.99M incident cost x 0.24048551839932833 exposure x 0.25951 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
No weakness class or product neighbourhood is held for this record, so this index cannot name anywhere to check next. That is an absence in the record, not a finding about the software.
Running PHP? 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.
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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: Proof-of-concept published · 1 public repository, 2025-09-08.
- RUNG 1Nothing observed in held sources
- RUNG 2Proof-of-concept published · 1 public repository2025-09-08receipt
- RUNG 3Exploited in the wild · CISA KEV listed
- RUNG 4Ransomware campaign use known
Affected & Fixed Versions as published
Show all 6 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
In PHP versions 7.3.x below 7.3.33, 7.4.x below 7.4.26 and 8.0.x below 8.0.13, certain XML parsing functions, like simplexml_load_file(), URL-decode the filename passed to them. If that filename contains URL-encoded NUL character, this may cause the function to interpret this as the end of the filename, thus interpreting the filename differently from what the user intended, which may lead it to reading a different file than intended. receipt
NVD's analysis a second authority
- severity
- 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- weakness
- CWE-159
- affected versions
- php >= 7.3.0 < 7.3.33; php >= 7.4.0 < 7.4.26; php >= 8.0.0 < 8.0.13; and 3 more, listed in full below
- also scored by
- [email protected] 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
check it yourself bugs.php.net security.netapp.com debian.org tenable.com lists.debian.org receipt
Movement the material steps
Show all 41 observations
41 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
Siblings and hubs
Records related to this one
None. No alias set, and nothing in the corpus cites this identifier or shares its product family within 60 days.
Browse the index from here
These are index-wide views, not findings about CVE-2021-21707.
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.