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Vulnerability record · CVE-2021-21707 · published 29 November 2021

CVE-2021-21707: Php vulnerability

Php · Php

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.

5.3 CVSS 3.1 Medium EPSS 26% · top 2.1% CWE-159 · CWE-159
5.3CVSS 3.1 base score, v2 5.0
26%EPSS exploitation probability, 30 days
NoNot in CISA KEV
4Affected product versions listed by NVD
10References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

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.

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

Affected products

4 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://bugs.php.net/bug.php?id=79971 ExploitIssue TrackingPatchRelease NotesVendor Advisory
https://lists.debian.org/debian-lts-announce/2022/12/msg00030.html Issue TrackingMailing List
https://security.netapp.com/advisory/ntap-20211223-0005/ Third Party Advisory
https://www.debian.org/security/2022/dsa-5082 Third Party Advisory
https://www.tenable.com/security/tns-2022-09 PatchRelease NotesThird Party Advisory
https://bugs.php.net/bug.php?id=79971 ExploitIssue TrackingPatchRelease NotesVendor Advisory
https://lists.debian.org/debian-lts-announce/2022/12/msg00030.html Issue TrackingMailing List
https://security.netapp.com/advisory/ntap-20211223-0005/ Third Party Advisory
https://www.debian.org/security/2022/dsa-5082 Third Party Advisory
https://www.tenable.com/security/tns-2022-09 PatchRelease NotesThird Party Advisory

Track CVE-2021-21707 inside VULONE

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Source: NIST National Vulnerability Database (record CVE-2021-21707), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.