CVE-2021-34798: NULL pointer dereference in httpd core
Vulnerability summary
CVE-2021-34798 is a high (CVSS 7.5) NULL Pointer Dereference vulnerability in apache software foundation apache http server. EPSS estimates a 64.51% chance of exploitation in the next 30 days, higher than 99.2% of scored vulnerabilities.
Severe, CVSS 7.5 (NVD); no exploitation reported by the 5 checked sources; EPSS 65% (FIRST, 03-11-2026)
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 14 · Related 7Timeline
- 16-09-2021PublishedVulnerability first disclosed.
- 04-08-2024Last modifiedVulnerability information updated.
Description
Malformed requests may cause the server to dereference a NULL pointer. This issue affects Apache HTTP Server 2.4.48 and earlier.
CVSS metrics
5 scores · 4 sources · 2 versions- OSV · AlpineEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · UbuntuEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated7.5HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
64.51%
Chance of exploitation in the next 30 days
Percentile
99%
Versus all other CVEs
30-day change
No change 0.00 pp
From 64.51% 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.
Oracle6 products
- communications_cloud_native_core_network_function_cloud_native_environment1.10.0
- enterprise_manager_base_platform13.4.0.0 | 13.5.0.0
- http_server12.2.1.3.0 | 12.2.1.4.0
- instantis_enterprisetrack17.1 | 17.2 | 17.3
- peoplesoft_enterprise_peopletools8.58
Netapp3 products
Debian2 products
- apache2< 2.4.49-1
- debian_linuxEOL9.0 | 10.0 | 11.0
Siemens2 products
Alpine1 product
- apache2< 2.4.49-r0
Apache1 product
- http_server≤ 2.4.48
Apache software foundation1 product
- apache http server≥ Apache HTTP Server 2.4, ≤ 2.4.48
Broadcom1 product
Fedoraproject1 product
- fedoraEOL34 | 35
Tenable1 product
- tenable.sc≤ 5.19.1
Ubuntu1 product
- apache2< 2.4.7-1ubuntu4.22+esm2 | < 2.4.18-2ubuntu3.17+esm2 | < 2.4.29-1ubuntu4.17 | < 2.4.41-4ubuntu3.5
11 vendors · 20 products
References
25 links
lists.debian.org/debian-lts-announce/2021/10/msg00001.htmlMailing ListX Refsource MLISTThird Party Advisory- tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-httpd-2.4.49-VWL69sWQVendor AdvisoryX Refsource CISCOThird Party Advisory
