CVE-2021-3537: debian debian_linux NULL Pointer Dereference
Vulnerability summary
CVE-2021-3537 is a medium (CVSS 5.9) NULL Pointer Dereference vulnerability in debian debian_linux. EPSS estimates a 3.60% chance of exploitation in the next 30 days, higher than 89.4% of scored vulnerabilities.
Not severe (CVSS 5.9, network access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 15 · Related 11Timeline
- 14-05-2021PublishedVulnerability first disclosed.
- 14-10-2026Last modifiedVulnerability information updated.
Description
A vulnerability found in libxml2 in versions before 2.9.11 shows that it did not propagate errors while parsing XML mixed content, causing a NULL dereference. If an untrusted XML document was parsed in recovery mode and post-validated, the flaw could be used to crash the application. The highest threat from this vulnerability is to system availability.
CVSS metrics
6 scores · 5 sources · 2 versions- OSV · AlpineEcosystem advisory · calculated5.9MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · UbuntuEcosystem advisory · calculated5.9MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated5.9MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · RubygemsEcosystem advisory · calculated5.9MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
3.60%
Chance of exploitation in the next 30 days
Percentile
89%
Versus all other CVEs
30-day change
Increase +0.09 pp
From 3.50% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.
Netapp7 products
- active_iq_unified_managerna
- clustered_data_ontapna
- clustered_data_ontap_antivirus_connectorna
- hci_h410c_firmwarena
- manageability_software_development_kitna
Oracle7 products
- communications_cloud_native_core_network_function_cloud_native_environment1.10.0
- enterprise_manager_base_platform13.4.0.0 | 13.5.0.0
- enterprise_manager_ops_center12.4.0.0
- mysql_workbench≤ 8.0.26
- openjdk8:update301
Debian2 products
- libxml2< 2.9.10+dfsg-6.6
- debian_linuxEOL9.0
Redhat2 products
- enterprise_linuxEOL6.0 | 7.0 | 8.0
- jboss_core_servicesna
Alpine1 product
- libxml2< 2.9.9-r5 | < 2.9.10-r5 | < 2.9.10-r6 | < 2.9.10-r7 | < 2.9.11-r0
Fedoraproject1 product
- fedoraEOL33 | 34
RubyGems1 product
- nokogiri< 1.11.4
Ubuntu1 product
- libxml2< 2.9.1+dfsg1-3ubuntu4.13+esm2 | < 2.9.3+dfsg1-1ubuntu0.7+esm1 | < 2.9.4+dfsg1-6.1ubuntu1.4 | < 2.9.10+dfsg-5ubuntu0.20.04.1
Xmlsoft1 product
- libxml2< 2.9.11
9 vendors · 23 products
References
27 links
lists.debian.org/debian-lts-announce/2021/05/msg00008.htmlMailing ListX Refsource MLISTWEBThird Party Advisory- bugzilla.redhat.com/show_bug.cgi?id=1956522X Refsource MISCWEBIssue TrackingPatchThird Party Advisory
