CVE-2004-0700: Format string vulnerability in the mod_proxy hook functions function in ssl_engine_log.c in mod_ssl before 2.8

This month

HIGH 7.5WATCHLISTDOWNGRADEMITIGATE

CVE-2004-0700 is a high-severity flaw (CVSS 7.5) affecting mod ssl, linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Format string vulnerability in the mod_proxy hook functions function in ssl_engine_log.c in mod_ssl before 2.8.19 for Apache before 1.3.31 may allow remote attackers to execute arbitrary messages via format string specifiers in certain log messages for HTTPS that are handled by the ssl_log function.

Why this priority

High severity
EPSS top 7%: very likely to be exploited
On your watchlist

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
EPSS exploit chance	5.8% (top 7%)
CISA exploited list	No
Published	2004-07-27
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: gentoo · mod ssl

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2004-07-27 04:00 UTCPublished CVE record published
2026-06-16 22:06 UTCUpdated Record last modified

mod ssl mod ssl DOWNGRADE

Affected: 2.3.11 · 2.4.0 · 2.4.1 · 2.4.2 · 2.4.3 · 2.4.4 · 2.4.5 · 2.4.6

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.3.11

1. Check installed version

apt-cache policy mod-ssl || rpm -q mod-ssl || mod-ssl --version

2. No fixed release: DOWNGRADE to a release before 2.3.11 (Debian / Ubuntu)

apt-cache madison mod-ssl sudo apt install mod-ssl=<VERSION_BEFORE_2.3.11> sudo apt-mark hold mod-ssl

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list mod-ssl sudo dnf downgrade mod-ssl-<VERSION_BEFORE_2.3.11> sudo dnf versionlock add mod-ssl

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

gentoo linux MITIGATE

Affected: 1.4

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.4

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2004-0700?

mod ssl: downgrade or apply the listed mitigation; linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2004-0700 being exploited?

CVE-2004-0700 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2004-0700 affect?

CVE-2004-0700 affects mod ssl, linux. Severity is high (CVSS 7.5). Format string vulnerability in the mod_proxy hook functions function in ssl_engine_log.c in mod_ssl before 2.8.19 for Apache before 1.3.31 may allow remote attackers to execute arbitrary messages via format string specifiers in certain log

How urgent is CVE-2004-0700?

Priority 55/100. High severity; EPSS top 7%: very likely to be exploited; On your watchlist

Related CVEs

CVE-2002-1157 HIGH 7.5 UPGRADE Cross-site scripting vulnerability in the mod_ssl Apache module 2.8.9 and earlier, when UseCanonicalName is of
CVE-2002-0653 HIGH 7.8 UPGRADE Off-by-one buffer overflow in the ssl_compat_directive function, as called by the rewrite_command hook for mod
CVE-2002-0082 HIGH 7.5 DOWNGRADE DOWNGRADE The dbm and shm session cache code in mod_ssl before 2.8.7-1.3.23, and Apache-SSL before 1.3.22+1.46, does not

References

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