Vulnerability · Published Jun 10, 2021 · Assigned by apache
CVE-2021-26691Apache HTTP Server mod_session response handling heap overflow
Critical 9.8
In plain English
A critical-severity heap buffer overflow in Apache HTTP Server from Apache Software Foundation. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 68.1% (higher than 99.3% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS NVD)9.8Critical
Exploit odds (30 days)68.1%top 0.7% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known
Official description
In Apache HTTP Server versions 2.4.0 to 2.4.46 a specially crafted SessionHeader sent by an origin server could cause a heap overflow
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:8 | httpd | 2.4.37-43.module_el8.5.0+2597+c4b14997.alma | ALSA-2021:4537 |
| AlmaLinux:8 | httpd-devel | 2.4.37-43.module_el8.5.0+2597+c4b14997.alma | ALSA-2021:4537 |
| AlmaLinux:8 | httpd-filesystem | 2.4.37-43.module_el8.5.0+2597+c4b14997.alma | ALSA-2021:4537 |
| AlmaLinux:8 | httpd-manual | 2.4.37-43.module_el8.5.0+2597+c4b14997.alma | ALSA-2021:4537 |
| AlmaLinux:8 | httpd-tools | 2.4.37-43.module_el8.5.0+2597+c4b14997.alma | ALSA-2021:4537 |
| AlmaLinux:8 | mod_http2 | 1.15.7-3.module_el8.5.0+2609+b30d9eec | ALSA-2021:3816 |
| AlmaLinux:8 | mod_http2 | 1.15.7-3.module_el8.5.0+2609+b30d9eec | ALSA-2021:4537 |
| AlmaLinux:8 | mod_ldap | 2.4.37-43.module_el8.5.0+2597+c4b14997.alma | ALSA-2021:4537 |
| AlmaLinux:8 | mod_md | 1:2.0.8-8.module_el8.5.0+2609+b30d9eec | ALSA-2021:4537 |
| AlmaLinux:8 | mod_md | 1:2.0.8-8.module_el8.6.0+2872+fe0ff7aa | ALSA-2021:4537 |
| AlmaLinux:8 | mod_md | 1:2.0.8-8.module_el8.6.0+2872+fe0ff7aa | ALSA-2021:3816 |
| AlmaLinux:8 | mod_md | 1:2.0.8-8.module_el8.5.0+2609+b30d9eec | ALSA-2021:3816 |
| AlmaLinux:8 | mod_proxy_html | 1:2.4.37-43.module_el8.5.0+2597+c4b14997.alma | ALSA-2021:4537 |
| AlmaLinux:8 | mod_session | 2.4.37-43.module_el8.5.0+2597+c4b14997.alma | ALSA-2021:4537 |
| AlmaLinux:8 | mod_ssl | 1:2.4.37-43.module_el8.5.0+2597+c4b14997.alma | ALSA-2021:4537 |
| Alpine:v3.20 | apache2 | 2.4.48-r0 | ALPINE-CVE-2021-26691 |
| Alpine:v3.21 | apache2 | 2.4.48-r0 | ALPINE-CVE-2021-26691 |
| Alpine:v3.22 | apache2 | 2.4.48-r0 | ALPINE-CVE-2021-26691 |
| Alpine:v3.23 | apache2 | 2.4.48-r0 | ALPINE-CVE-2021-26691 |
| Alpine:v3.24 | apache2 | 2.4.48-r0 | ALPINE-CVE-2021-26691 |
| Debian:12 | apache2 | 2.4.46-6 | DEBIAN-CVE-2021-26691 |
| Debian:13 | apache2 | 2.4.46-6 | DEBIAN-CVE-2021-26691 |
| Debian:14 | apache2 | 2.4.46-6 | DEBIAN-CVE-2021-26691 |
| Rocky Linux:8 | httpd | 0:2.4.37-39.module+el8.4.0+571+fd70afb1 | RLSA-2021:3816 |
| Rocky Linux:8 | mod_http2 | 0:1.15.7-3.module+el8.5.0+695+1fa8055e | RLSA-2021:3816 |
| Rocky Linux:8 | mod_http2 | 0:1.15.7-3.module+el8.4.0+553+7a69454b | RLSA-2021:3816 |
| Rocky Linux:8 | mod_md | 1:2.0.8-8.module+el8.4.0+553+7a69454b | RLSA-2021:3816 |
| Rocky Linux:8 | mod_md | 1:2.0.8-8.module+el8.5.0+695+1fa8055e | RLSA-2021:3816 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Apache Software Foundation | Apache HTTP Server | 2.4.462.4.432.4.412.4.392.4.382.4.372.4.352.4.34 |
Weakness: CWE-122
References
- http://httpd.apache.org/security/vulnerabilities_24.html x_refsource_MISC
- https://lists.apache.org/thread.html/re026d3da9d7824bd93b9f871c0fdda978d960c7e62d8c43cba8d0bf3%40%3Ccvs.httpd.apache.org%3E x_refsource_MISC
- [httpd-announce] 20210609 CVE-2021-26691: mod_session response handling heap overflow mailing-list, x_refsource_MLIST
- [httpd-dev] 20210610 Re: svn commit: r1890598 - in /httpd/site/trunk/content/security/json: CVE-2019-17567.json CVE-2020-13938.json CVE-2020-13950.json CVE-2020-35452.json CVE-2021-26690.json CVE-2021-26691.json CVE-2021-30641.json CVE-2021-31618.json mailing-list, x_refsource_MLIST
- [oss-security] 20210609 CVE-2021-26691: Apache httpd: mod_session response handling heap overflow mailing-list, x_refsource_MLIST
- [debian-lts-announce] 20210709 [SECURITY] [DLA 2706-1] apache2 security update mailing-list, x_refsource_MLIST
- DSA-4937 vendor-advisory, x_refsource_DEBIAN
- GLSA-202107-38 vendor-advisory, x_refsource_GENTOO
- FEDORA-2021-dce7e7738e vendor-advisory, x_refsource_FEDORA
- FEDORA-2021-e3f6dd670d vendor-advisory, x_refsource_FEDORA
- https://www.oracle.com/security-alerts/cpuoct2021.html x_refsource_MISC
- https://security.netapp.com/advisory/ntap-20210702-0001/ x_refsource_CONFIRM
- https://www.oracle.com/security-alerts/cpujan2022.html x_refsource_MISC