CVE-2018-10243: htp_parse_authorization_digest in htp_parsers.c in LibHTP 0.5.26 allows remote attackers to cause a heap-based

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CRITICAL 9.8REMOTEDOWNGRADE

CVE-2018-10243 is a critical-severity flaw (CVSS 9.8) affecting libhtp. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

htp_parse_authorization_digest in htp_parsers.c in LibHTP 0.5.26 allows remote attackers to cause a heap-based buffer over-read via an authorization digest header.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.3% (top 17%)
CISA exploited list	No
Weakness	CWE-125
Published	2019-04-04
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: oisf

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2019-04-04 16:29 UTCPublished CVE record published
2026-06-17 01:33 UTCUpdated Record last modified

oisf libhtp DOWNGRADE

Affected: 0.5.26

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.5.26

1. Check installed version

apt-cache policy libhtp || rpm -q libhtp || libhtp --version

2. No fixed release: DOWNGRADE to a release before 0.5.26 (Debian / Ubuntu)

apt-cache madison libhtp sudo apt install libhtp=<VERSION_BEFORE_0.5.26> sudo apt-mark hold libhtp

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

dnf --showduplicates list libhtp sudo dnf downgrade libhtp-<VERSION_BEFORE_0.5.26> sudo dnf versionlock add libhtp

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.

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-2018-10243?

libhtp: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2018-10243 being exploited?

CVE-2018-10243 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-2018-10243 affect?

CVE-2018-10243 affects libhtp. Severity is critical (CVSS 9.8). htp_parse_authorization_digest in htp_parsers.c in LibHTP 0.5.26 allows remote attackers to cause a heap-based buffer over-read via an authorization digest header.

How urgent is CVE-2018-10243?

Priority 60/100. Critical severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2025-53537 HIGH 7.5 UPGRADE LibHTP is a security-aware parser for the HTTP protocol and its related bits and pieces
CVE-2024-45797 HIGH 7.5 UPGRADE LibHTP is a security-aware parser for the HTTP protocol and the related bits and pieces
CVE-2024-28871 HIGH 7.5 DOWNGRADE LibHTP is a security-aware parser for the HTTP protocol and the related bits and pieces
CVE-2024-23837 HIGH 7.5 UPGRADE MITIGATE LibHTP is a security-aware parser for the HTTP protocol
CVE-2019-17420 MEDIUM 5.3 UPGRADE DOWNGRADE In OISF LibHTP before 0.5.31, as used in Suricata 4.1.4 and other products, an HTTP protocol parsing error cau

References

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