CVE-2021-34798
No exploitation reported by the sources we read.
- Published2021-09-16
- WeaknessCWE-476
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
Description
Malformed requests may cause the server to dereference a NULL pointer. This issue affects Apache HTTP Server 2.4.48 and earlier.
Timeline
dates in UTC- 2021-09-1615:15CVE publishedNVD
- 2026-10-2319:23EPSS crossed 10 %FIRST EPSS
Observed activity
isMalicious corpus · updated 2026-10-23 21:37 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-34798?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-34798?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
NVD| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 9.0 | = 9.0 | no fix published | NVD |
| 10.0 | = 10.0 | no fix published | NVD |
| 11.0 | = 11.0 | no fix published | NVD |
| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 17.1 | = 17.1 | no fix published | NVD |
| 17.2 | = 17.2 | no fix published | NVD |
| 17.3 | = 17.3 | no fix published | NVD |
| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 34.x | = 34 | no fix published | NVD |
| 35.x | = 35 | no fix published | NVD |
16 more products in the sources.
as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.
Distribution builds and vendor advisories
Packages from OSV.dev and products from the vendors' CSAF advisories.
version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.
Packages
- httpdAlmaLinux:8all versions · fixed in 2.4.37-43.module_el8.5.0+2630+51c6d843.2.almaand 6 other packages
- mod_mdAlmaLinux:8all versions · fixed in 1:2.0.8-8.module_el8.6.0+2872+fe0ff7aa
- mod_sslAlmaLinux:8all versions · fixed in 1:2.4.37-43.module_el8.5.0+2630+51c6d843.2.almaand 1 other package
Fix
Advisories and patches
- httpd.apache.orgRelease Notes · Vendor Advisory
- cert-portal.siemens.comPatch
- www.oracle.comPatch
- www.oracle.comPatch
Detection
- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- none listed PoC-in-GitHub
Sources
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Published
- 2021-09-16
- Last Modified
- 2026-06-17
- NVD status
- Modified
Frequently asked questions
What is CVE-2021-34798?
Is CVE-2021-34798 actively exploited?
What is the CVSS score for CVE-2021-34798?
Running Apache HTTP Server? Hear about its next vulnerability
Surveillance reads the versions in your stack — a domain, a lockfile or a list — checks each CVE against the ranges its sources publish, and alerts you when one you run is exploited or enters CISA KEV. A version it cannot read stays « version not verified ».
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Go further
- Following what attackers exploit right now? The CISA KEV additions of the month, with their patch deadlines.
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Related vulnerabilities
Same product first, then the same vendor advisory and the same publication week.