# CVE-2026-49975: Apache HTTP Server: mod_http2 denial of service > Attackers can cause denial of service in Apache HTTP Server by sending malicious HTTP requests that trigger excessive memory allocation. - **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 8 Jun 2026 - **Updated:** 19 Aug 2026 - **Also known as:** ALPINE-CVE-2026-49975, ALSA-2026:25057, ALSA-2026:25090, ALSA-2026:25225, AZL-89510, AZL-89550, AZL-89760, BELL-CVE-2026-49975, BIT-apache-2026-49975, CLSA-2026-1781259837, CLSA-2026-1781511735, CLSA-2026-1782153735, CLSA-2026-1782317138, CLSA-2026-1782317575, CLSA-2026-1782317620, CLSA-2026-1783525080, CLSA-2026-1783632803, CLSA-2026-1783633126, CLSA-2026-1783791892, CLSA-2026-1783791996, CLSA-2026-1783792262, CLSA-2026-1787249757, CLSA-2026-1787249820, CLSA-2026-1787250962, CLSA-2026-1787250980, CLSA-2026-1787251196, CLSA-2026-1787251292, CLSA-2026-1787251300, CLSA-2026-1787251550, CLSA-2026-1787251557, CLSA-2026-1790158682, CLSA-2026-1790236505, CLSA-2026-1790262589, DEBIAN-CVE-2026-49975, ECHO-c67b-44b0-ff31, GHSA-262v-g5h9-6mc6, MINI-97wj-wmfr-hrwh, OESA-2026-2611, OESA-2026-2627, OESA-2026-2638, OESA-2026-2639, OESA-2026-2640, RHSA-2026:25057, RHSA-2026:25090, RHSA-2026:25225, RLSA-2026:25057, RLSA-2026:25090, RLSA-2026:25225, UBUNTU-CVE-2026-49975, USN-8384-1, USN-8398-1, USN-8398-3, USN-8398-4 ## What is CVE-2026-49975? CVE-2026-49975 is a high-severity denial of service vulnerability in Apache Http Server, published on 8 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description Memory Allocation with Excessive Size Value vulnerability in Apache HTTP Server's mod_http leads to denial of service via malicious HTTP requests. This issue affects Apache HTTP Server: from 2.4.17 through 2.4.67. Weakness: CWE-409 (Improper Handling of Highly Compressed Data (Data Amplification)), CWE-789 (Memory Allocation with Excessive Size Value) ## Which versions are affected by CVE-2026-49975? 1 open source package ship an affected version, including apache. It affects 2 products. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `apache` | Bitnami | From 2.4.17 | 2.4.68 | | `mod_http2` | AlmaLinux:10 | All versions | 2.0.29-4.el10_2.1 | | `httpd` | AlmaLinux:8 | All versions | 2.4.37-65.module_el8.10.0+4185+0955a0d7.8 | | `httpd` | AlmaLinux:8 | All versions | 2.4.37-65.module_el8.10.0+4190+704ad79b.8 | | `httpd-devel` | AlmaLinux:8 | All versions | 2.4.37-65.module_el8.10.0+4185+0955a0d7.8 | | `httpd-devel` | AlmaLinux:8 | All versions | 2.4.37-65.module_el8.10.0+4190+704ad79b.8 | | `httpd-filesystem` | AlmaLinux:8 | All versions | 2.4.37-65.module_el8.10.0+4185+0955a0d7.8 | | `httpd-manual` | AlmaLinux:8 | All versions | 2.4.37-65.module_el8.10.0+4185+0955a0d7.8 | | `httpd-tools` | AlmaLinux:8 | All versions | 2.4.37-65.module_el8.10.0+4185+0955a0d7.8 | | `httpd-tools` | AlmaLinux:8 | All versions | 2.4.37-65.module_el8.10.0+4190+704ad79b.8 | | `mod_http2` | AlmaLinux:8 | All versions | 1.15.7-10.module_el8.10.0+4190+704ad79b.6 | | `mod_ldap` | AlmaLinux:8 | All versions | 2.4.37-65.module_el8.10.0+4185+0955a0d7.8 | | `mod_ldap` | AlmaLinux:8 | All versions | 2.4.37-65.module_el8.10.0+4190+704ad79b.8 | | `mod_md` | AlmaLinux:8 | All versions | 1:2.0.8-8.module_el8.10.0+4088+57f011c1.2 | | `mod_proxy_html` | AlmaLinux:8 | All versions | 1:2.4.37-65.module_el8.10.0+4185+0955a0d7.8 | | `mod_proxy_html` | AlmaLinux:8 | All versions | 1:2.4.37-65.module_el8.10.0+4190+704ad79b.8 | | `mod_session` | AlmaLinux:8 | All versions | 2.4.37-65.module_el8.10.0+4185+0955a0d7.8 | | `mod_session` | AlmaLinux:8 | All versions | 2.4.37-65.module_el8.10.0+4190+704ad79b.8 | | `mod_ssl` | AlmaLinux:8 | All versions | 1:2.4.37-65.module_el8.10.0+4185+0955a0d7.8 | | `mod_ssl` | AlmaLinux:8 | All versions | 1:2.4.37-65.module_el8.10.0+4190+704ad79b.8 | | `mod_http2` | AlmaLinux:9 | All versions | 2.0.26-6.el9_8.1 | | `mod_http2` | Red Hat:enterprise_linux:10.2 | All versions | 0:2.0.29-4.el10_2.1 | | `mod_http2-debuginfo` | Red Hat:enterprise_linux:10.2 | All versions | 0:2.0.29-4.el10_2.1 | | `mod_http2-debugsource` | Red Hat:enterprise_linux:10.2 | All versions | 0:2.0.29-4.el10_2.1 | | `httpd` | Red Hat:enterprise_linux:8::appstream | All versions | 0:2.4.37-65.module+el8.10.0+24281+ea10630c.8 | | `httpd-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 0:2.4.37-65.module+el8.10.0+24281+ea10630c.8 | | `httpd-debugsource` | Red Hat:enterprise_linux:8::appstream | All versions | 0:2.4.37-65.module+el8.10.0+24281+ea10630c.8 | | `httpd-devel` | Red Hat:enterprise_linux:8::appstream | All versions | 0:2.4.37-65.module+el8.10.0+24281+ea10630c.8 | | `httpd-filesystem` | Red Hat:enterprise_linux:8::appstream | All versions | 0:2.4.37-65.module+el8.10.0+24281+ea10630c.8 | | `httpd-manual` | Red Hat:enterprise_linux:8::appstream | All versions | 0:2.4.37-65.module+el8.10.0+24281+ea10630c.8 | | `httpd-tools` | Red Hat:enterprise_linux:8::appstream | All versions | 0:2.4.37-65.module+el8.10.0+24281+ea10630c.8 | | `httpd-tools-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 0:2.4.37-65.module+el8.10.0+24281+ea10630c.8 | | `mod_http2` | Red Hat:enterprise_linux:8::appstream | All versions | 0:1.15.7-10.module+el8.10.0+24368+ad388a0c.6 | | `mod_http2-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 0:1.15.7-10.module+el8.10.0+24368+ad388a0c.6 | | `mod_http2-debugsource` | Red Hat:enterprise_linux:8::appstream | All versions | 0:1.15.7-10.module+el8.10.0+24368+ad388a0c.6 | | `mod_ldap` | Red Hat:enterprise_linux:8::appstream | All versions | 0:2.4.37-65.module+el8.10.0+24281+ea10630c.8 | | `mod_ldap-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 0:2.4.37-65.module+el8.10.0+24281+ea10630c.8 | | `mod_md` | Red Hat:enterprise_linux:8::appstream | All versions | 1:2.0.8-8.module+el8.10.0+23815+1b5e1c66.2 | | `mod_md-debuginfo` | Red Hat:enterprise_linux:8::appstream | All versions | 1:2.0.8-8.module+el8.10.0+23815+1b5e1c66.2 | | `mod_md-debugsource` | Red Hat:enterprise_linux:8::appstream | All versions | 1:2.0.8-8.module+el8.10.0+23815+1b5e1c66.2 | Products: Apache Http Server, Debian Debian Linux. ## How do I fix CVE-2026-49975? Upgrade apache to 2.4.68 or later. ## Is CVE-2026-49975 being exploited? It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-49975 exists. Public exploit code: - HTTP/2 Bomb PoC — CVE-2026-49975 (HPACK indexed reference bomb + flow-control stall) (github_poc): https://github.com/mrx-arafat/CVE-2026-49975-POC - HTTP/2 Bomb (github_poc): https://github.com/EQSTLab/CVE-2026-49975 - PoC de CVE-2026-49975 (HTTP/2 Bomb): DoS remoto contra servidores web con HTTP/2 por defecto. (github_poc): https://github.com/fevar54/Proof-of-Concept-POC---CVE-2026-49975-HTTP-2-Bomb- - CVE-2026-49975漏洞复现 (github_poc): https://github.com/LSG-PolarBear/CVE-2026-49975 - CVE-2026-49975 HTTP/2 Stream Amplification — Docker PoC with Web Console (github_poc): https://github.com/obrige/http2-bomb - CVE-2026-49975 (github_poc): https://github.com/LiaoZiqi-GZFLS/CVE-2026-49975 ## Other vulnerabilities in Apache Http Server - [CVE-2021-42013](https://insights.sbomify.com/CVE-2021-42013/): Apache HTTP Server Path Traversal (critical 9.8, exploited in the wild) - [CVE-2024-38475](https://insights.sbomify.com/CVE-2024-38475/): Apache HTTP Server Improper Escaping of Output (critical 9.1, exploited in the wild) - [CVE-2021-40438](https://insights.sbomify.com/CVE-2021-40438/): Apache HTTP Server-Side Request Forgery (SSRF) (critical 9.0, exploited in the wild) - [CVE-2019-0211](https://insights.sbomify.com/CVE-2019-0211/): Apache HTTP Server Privilege Escalation (high 7.8, exploited in the wild) - [CVE-2021-41773](https://insights.sbomify.com/CVE-2021-41773/): Apache HTTP Server Path Traversal (high 7.5, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-49975 and fix it if it is affected. What it is: CVE-2026-49975 is a high-severity denial of service vulnerability in Apache Http Server, published on 8 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-49975 exists. Affected packages and fixed versions: - apache (Bitnami): affected from 2.4.17; fixed in 2.4.68 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-49975/ (Markdown: https://insights.sbomify.com/CVE-2026-49975/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-49975 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-49975 - OSV: https://osv.dev/vulnerability/CVE-2026-49975 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-49975/ Summaries are generated and may contain mistakes; the official description above is the record.