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Fencer Vulns
high 7.5

CVE-2025-55753 json

Apache HTTP Server: mod_md (ACME), unintended retry intervals

published 2025-12-05 11 mo ago modified 2026-10-18 21 d ago also BIT-apache-2025-55753 , EUVD-2025-201395

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 41%
public exploits
0
none known

Summary

An integer overflow in the case of failed ACME certificate renewal leads, after a number of failures (~30 days in default configurations), to the backoff timer becoming 0. Attempts to renew the certificate then are repeated without delays until it succeeds.

This issue affects Apache HTTP Server: from 2.4.30 before 2.4.66.

Users are recommended to upgrade to version 2.4.66, which fixes the issue.

Patch / fix

  • bitnami apache 2.4.66
  • Apache Software Foundation Apache HTTP Server 2.4.66
  • apache2 Debian 12 2.4.66-1~deb12u1
  • apache2 Debian 13 2.4.66-1~deb13u1
  • apache2 Debian 14 2.4.66-1

debian advisories DEBIAN-CVE-2025-55753

  • apache2 Ubuntu 22.04 LTS 2.4.52-1ubuntu4.18
  • apache2 Ubuntu 24.04 LTS 2.4.58-1ubuntu8.10
  • apache2 Ubuntu 25.10 2.4.64-1ubuntu3.2
  • apache2 Ubuntu 26.04 LTS 2.4.66-2ubuntu1
  • apache2 Ubuntu Pro 20.04 LTS 2.4.41-4ubuntu3.23+esm3

ubuntu advisories UBUNTU-CVE-2025-55753

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • jbcs-httpd24-curl jboss core services 1 8.11.0-4.el7jbcs
  • jbcs-httpd24-httpd jboss core services 1 2.4.62-11.el7jbcs
  • jbcs-httpd24-httpd jboss core services 1 2.4.62-11.el8jbcs
  • jbcs-httpd24-mod_jk jboss core services 1 1.2.50-12.redhat_1.el7jbcs
  • jbcs-httpd24-mod_jk jboss core services 1 1.2.50-12.redhat_1.el8jbcs
  • jbcs-httpd24-mod_md jboss core services 1 1:2.4.28-13.el7jbcs
  • jbcs-httpd24-mod_md jboss core services 1 1:2.4.28-13.el8jbcs
  • jbcs-httpd24-libcurl jboss core services 1 8.11.0-4.el7jbcs

red hat advisories RHSA-2026:2994RHSA-2026:0094RHSA-2026:0092RHSA-2026:0093RHSA-2026:0029RHSA-2026:0030

  • apache2 SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +5 more 2.4.66-150400.6.57.1
  • apache2 SLES for SAP applications 16.0, SLES 16.0 2.4.63-160000.3.1
  • apache2-event SLES for SAP applications 16.0, SLES 16.0 2.4.63-160000.3.1
  • apache2-utils SLES for SAP applications 16.0, SLES 16.0 2.4.63-160000.3.1
  • apache2-manual SLES for SAP applications 16.0, SLES 16.0 2.4.63-160000.3.1
  • apache2-worker SLES for SAP applications 16.0, SLES 16.0 2.4.63-160000.3.1
  • apache2-prefork SLES for SAP applications 16.0, SLES 16.0 2.4.63-160000.3.1
  • apache2 SLES for SAP 15 SP6, SLES 15 SP6-LTSS, openSUSE Leap 15.6 2.4.58-150600.5.41.1

suse advisories SUSE-SU-2026:2686-1SUSE-SU-2026:20081-1SUSE-SU-2026:0020-1SUSE-SU-2026:0019-1SUSE-SU-2025:4518-1SUSE-SU-2025:4488-1

  • apache2 openSUSE Leap 16.0 2.4.63-160000.3.1
  • apache2-event openSUSE Leap 16.0 2.4.63-160000.3.1
  • apache2-utils openSUSE Leap 16.0 2.4.63-160000.3.1
  • apache2-manual openSUSE Leap 16.0 2.4.63-160000.3.1
  • apache2-worker openSUSE Leap 16.0 2.4.63-160000.3.1
  • apache2-prefork openSUSE Leap 16.0 2.4.63-160000.3.1
  • apache2 openSUSE Tumbleweed 2.4.66-1.1

opensuse advisories openSUSE-SU-2026:20030-1openSUSE-SU-2025:15808-1

  • httpd AlmaLinux 8 2.4.37-65.module_el8.10.0+4088+57f011c1.7
  • mod_md AlmaLinux 8 1:2.0.8-8.module_el8.10.0+4088+57f011c1.2
  • mod_ssl AlmaLinux 8 1:2.4.37-65.module_el8.10.0+4088+57f011c1.7
  • mod_ldap AlmaLinux 8 2.4.37-65.module_el8.10.0+4088+57f011c1.7
  • mod_http2 AlmaLinux 8 1.15.7-10.module_el8.10.0+4044+ea5f78b1.4
  • httpd-tools AlmaLinux 8 2.4.37-65.module_el8.10.0+4088+57f011c1.7
  • mod_session AlmaLinux 8 2.4.37-65.module_el8.10.0+4088+57f011c1.7
  • httpd-manual AlmaLinux 8 2.4.37-65.module_el8.10.0+4088+57f011c1.7

almalinux advisories ALSA-2025:23732ALSA-2025:23738ALSA-2025:23739

  • mod_md Rocky Linux 10 1:2.4.26-4.el10_1
  • mod_md Rocky Linux 9 1:2.4.26-1.el9_7.1
  • httpd Rocky Linux 8 2.4.37-65.module+el8.10.0+40045+6ce8579b.6
  • httpd Rocky Linux 8 2.4.37-65.module+el8.10.0+1830+22f0c9e0
  • httpd Rocky Linux 8 2.4.37-65.module+el8.10.0+1842+4a9649e8.2
  • httpd Rocky Linux 8 2.4.37-65.module+el8.10.0+1938+3b7755d4.3
  • httpd Rocky Linux 8 2.4.37-65.module+el8.10.0+1840+b070a976.1
  • httpd Rocky Linux 8 2.4.37-65.module+el8.10.0+2061+8d03fdec.5

rocky linux advisories RLSA-2025:23738RLSA-2025:23739RLSA-2025:23732

  • apache2 Alpine 3.24, Alpine 3.23, Alpine 3.22 +2 more 2.4.66-r0

alpine advisories ALPINE-CVE-2025-55753

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • httpd CBL-Mariner 2.0, Azure Linux 3.0 2.4.66-1

azure linux advisories AZL-71863AZL-71870

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-55753 updated cvss 7.5

mod_md: Apache HTTP Server: mod_md (ACME), unintended retry intervals

  • Red Hat Enterprise Linux AppStream (v. 8) mod_md 2.0.8-8.module+el8.10.0+23815+1b5e1c66.2, httpd 2.4.37-65.module+el8.10.0+23815+1b5e1c66.7, mod_ssl 2.4.37-65.module+el8.10.0+23815+1b5e1c66.7, mod_ldap 2.4.37-65.module+el8.10.0+23815+1b5e1c66.7, mod_http2 1.15.7-10.module+el8.10.0+23369+11a81384.4, httpd-tools 2.4.37-65.module+el8.10.0+23815+1b5e1c66.7, +4 more
    fixed: vendor fix RHSA-2025:23732
  • Red Hat Enterprise Linux AppStream (v. 9) mod_md 2.4.26-1.el9_7.1
    fixed: vendor fix RHSA-2025:23739
  • Red Hat Enterprise Linux AppStream (v. 10) mod_md 2.4.26-4.el10_1
    fixed: vendor fix RHSA-2025:23738
  • Red Hat Enterprise Linux AppStream AUS (v. 8.2) mod_md 2.0.8-7.module+el8.2.0+23841+60fa4803.1, httpd 2.4.37-21.module+el8.2.0+23841+60fa4803.11, mod_http2 1.11.3-3.module+el8.2.0+23461+1d03af5c.5, mod_ssl 2.4.37-21.module+el8.2.0+23841+60fa4803.11, mod_ldap 2.4.37-21.module+el8.2.0+23841+60fa4803.11, httpd-tools 2.4.37-21.module+el8.2.0+23841+60fa4803.11, +4 more
    fixed: vendor fix RHSA-2026:0009
  • Red Hat Enterprise Linux AppStream AUS (v.8.4) mod_md 2.0.8-8.module+el8.4.0+23842+00253415.1, httpd 2.4.37-39.module+el8.4.0+23842+00253415.11, mod_http2 1.15.7-3.module+el8.4.0+23462+1fa78ba3.4, mod_ssl 2.4.37-39.module+el8.4.0+23842+00253415.11, mod_ldap 2.4.37-39.module+el8.4.0+23842+00253415.11, httpd-tools 2.4.37-39.module+el8.4.0+23842+00253415.11, +4 more
    fixed: vendor fix RHSA-2026:0010
  • Red Hat Enterprise Linux AppStream AUS (v.8.6) mod_md 2.0.8-8.module+el8.6.0+23843+c27a5dc4.1, httpd 2.4.37-47.module+el8.6.0+23843+c27a5dc4.12, mod_http2 1.15.7-5.module+el8.6.0+23463+5d5709c6.4, mod_ssl 2.4.37-47.module+el8.6.0+23843+c27a5dc4.12, mod_ldap 2.4.37-47.module+el8.6.0+23843+c27a5dc4.12, httpd-tools 2.4.37-47.module+el8.6.0+23843+c27a5dc4.12, +4 more Red Hat Enterprise Linux AppStream E4S (v.8.6) mod_md 2.0.8-8.module+el8.6.0+23843+c27a5dc4.1, httpd 2.4.37-47.module+el8.6.0+23843+c27a5dc4.12, mod_http2 1.15.7-5.module+el8.6.0+23463+5d5709c6.4, mod_ssl 2.4.37-47.module+el8.6.0+23843+c27a5dc4.12, mod_ldap 2.4.37-47.module+el8.6.0+23843+c27a5dc4.12, httpd-tools 2.4.37-47.module+el8.6.0+23843+c27a5dc4.12, +4 more
    fixed: vendor fix RHSA-2026:0011
  • Red Hat Enterprise Linux AppStream E4S (v.8.8) mod_md 2.0.8-8.module+el8.8.0+23840+d7e7db80.1, httpd 2.4.37-56.module+el8.8.0+23840+d7e7db80.11, mod_http2 1.15.7-8.module+el8.8.0+23464+a2e0c444.6, mod_ssl 2.4.37-56.module+el8.8.0+23840+d7e7db80.11, mod_ldap 2.4.37-56.module+el8.8.0+23840+d7e7db80.11, httpd-tools 2.4.37-56.module+el8.8.0+23840+d7e7db80.11, +4 more
    fixed: vendor fix RHSA-2026:0012
  • Red Hat Enterprise Linux AppStream E4S (v.9.0) mod_md 2.4.0-3.el9_0.1
    fixed: vendor fix RHSA-2026:0092
show 10 more
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) mod_md 2.4.19-1.el9_2.1
    fixed: vendor fix RHSA-2026:0030
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) mod_md 2.4.26-3.el10_0.1
    fixed: vendor fix RHSA-2026:0093
  • Red Hat Enterprise Linux AppStream EUS (v.9.4) mod_md 2.4.19-1.el9_4.1
    fixed: vendor fix RHSA-2026:0029
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) mod_md 2.4.26-1.el9_6.1
    fixed: vendor fix RHSA-2026:0094
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) mod_md 2.0.8-8.module+el8.4.0+23842+00253415.1, httpd 2.4.37-39.module+el8.4.0+23842+00253415.11, mod_http2 1.15.7-3.module+el8.4.0+23462+1fa78ba3.4, mod_ssl 2.4.37-39.module+el8.4.0+23842+00253415.11, mod_ldap 2.4.37-39.module+el8.4.0+23842+00253415.11, httpd-tools 2.4.37-39.module+el8.4.0+23842+00253415.11, +4 more
    fixed: vendor fix RHSA-2026:0010
  • Red Hat Enterprise Linux AppStream TUS (v.8.6) mod_md 2.0.8-8.module+el8.6.0+23843+c27a5dc4.1, httpd 2.4.37-47.module+el8.6.0+23843+c27a5dc4.12, mod_http2 1.15.7-5.module+el8.6.0+23463+5d5709c6.4, mod_ssl 2.4.37-47.module+el8.6.0+23843+c27a5dc4.12, mod_ldap 2.4.37-47.module+el8.6.0+23843+c27a5dc4.12, httpd-tools 2.4.37-47.module+el8.6.0+23843+c27a5dc4.12, +4 more
    fixed: vendor fix RHSA-2026:0011
  • Red Hat Enterprise Linux AppStream TUS (v.8.8) mod_md 2.0.8-8.module+el8.8.0+23840+d7e7db80.1, httpd 2.4.37-56.module+el8.8.0+23840+d7e7db80.11, mod_http2 1.15.7-8.module+el8.8.0+23464+a2e0c444.6, mod_ssl 2.4.37-56.module+el8.8.0+23840+d7e7db80.11, mod_ldap 2.4.37-56.module+el8.8.0+23840+d7e7db80.11, httpd-tools 2.4.37-56.module+el8.8.0+23840+d7e7db80.11, +4 more
    fixed: vendor fix RHSA-2026:0012
  • Red Hat JBoss Core Services 2.4.62.SP3
    fixed: vendor fix RHSA-2026:2995
  • Red Hat JBoss Core Services on RHEL 7 Server jbcs-httpd24-mod_md 2.4.28-13.el7jbcs Red Hat JBoss Core Services on RHEL 8 jbcs-httpd24-mod_md 2.4.28-13.el8jbcs
    fixed: vendor fix RHSA-2026:2994
  • Red Hat Enterprise Linux 6 httpd, mod_ssl, httpd-tools, httpd-manual Red Hat Enterprise Linux 7 httpd, mod_ssl, mod_ldap, httpd-tools, mod_session, httpd-manual, +1 more Red Hat JBoss Core Services on RHEL 7 Server jbcs-httpd24-curl 8.11.0-4.el7jbcs, jbcs-httpd24-httpd 2.4.62-11.el7jbcs, jbcs-httpd24-apr-util 1.6.3-4.el7jbcs, jbcs-httpd24-libcurl 8.11.0-4.el7jbcs, jbcs-httpd24-mod_ssl 2.4.62-11.el7jbcs, jbcs-httpd24-openssl 1.1.1k-21.el7jbcs, +22 more Red Hat JBoss Core Services on RHEL 8 jbcs-httpd24-httpd 2.4.62-11.el8jbcs, jbcs-httpd24-apr-util 1.6.3-4.el8jbcs, jbcs-httpd24-mod_ssl 2.4.62-11.el8jbcs, jbcs-httpd24-mod_http2 2.0.29-8.el8jbcs, jbcs-httpd24-mod_ldap 2.4.62-11.el8jbcs, jbcs-httpd24-apr-util-nss 1.6.3-4.el8jbcs, +15 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
11 mo ago

Exploit prediction

0.48% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
bitnami apache
>=2.4.30, <2.4.66
2.4.66

Affected products

  • Apache Software Foundation Apache HTTP Server

Classification

Weakness
  • CWE-190 Integer Overflow or Wraparound
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.