CVE-2018-0733 [Medium] | Security Vulnerability in Openssl

Because of an implementation bug the PA-RISC CRYPTO_memcmp function is effectively reduced to only comparing the least significant bit of each byte. This allows an attacker to forge messages that would be considered as authenticated in an amount of tries lower than that guaranteed by the security claims of the scheme. The module can only be compiled by the HP-UX assembler, so that only HP-UX PA-RISC targets are affected. Fixed in OpenSSL 1.1.0h (Affected 1.1.0-1.1.0g).

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	2.23%	8.64%	+6.40%
2	2026-03-22	1.96%	2.23%	+0.28%
3	2025-12-28	—	1.96%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

2.23%

8.64%

+6.40%

2026-03-22

1.96%

2.23%

+0.28%

2025-12-28

—

1.96%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
5.9	3.0	MEDIUM	`CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:N) Service keeps running; no real outage angle.	2.2	3.6	[email protected]
4.3	2.0	MEDIUM	`AV:N/AC:M/Au:N/C:N/I:P/A:N` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:M) Exploitation needs some favorable conditions, but not exceptional ones. Authentication (AU:N) No authentication is required. Confidentiality impact (C:N) No confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:N) No availability impact.	8.6	2.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

5.9

3.0

MEDIUM

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N): Service keeps running; no real outage angle.

2.2

3.6

[email protected]

4.3

2.0

MEDIUM

AV:N/AC:M/Au:N/C:N/I:P/A:N Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:M): Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:N): No confidentiality impact.
Integrity impact (I:P): Partial integrity impact.
Availability impact (A:N): No availability impact.

8.6

2.9

[email protected]

OS Trackers for CVE-2018-0733

vendor	priority	summary	link
`debian`	unimportant	CVE-2018-0733 unimportant priority: Debian including 1 source packages (openssl), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5.	https://security-tracker.debian.org/tracker/CVE-2018-0733
`gentoo`	normal	CVE-2018-0733: 1 GLSA(s) (201811-21), 1 atom(s) (dev-libs/openssl); latest impact normal.	https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2018-0733
`redhat`	medium	—	https://access.redhat.com/security/cve/CVE-2018-0733
`ubuntu`	medium	CVE-2018-0733 medium priority: Ubuntu including 3 source packages (openssl, openssl098, openssl1.0), 12 status rows across 4 suites (artful, trusty, upstream, xenial): DNE 6, needs-triage 3, not-affected 3.	https://ubuntu.com/security/CVE-2018-0733

Affected software / configurations for CVE-2018-0733

Vendor	Product	Version	Raw CPE
openssl	openssl	>= 1.1.0, <= 1.1.0g	cpe:2.3:a:openssl:openssl::::::::

References for CVE-2018-0733

URL	Tags
http://www.oracle.com/technetwork/security-advisory/cpujul2018-4258247.html
http://www.oracle.com/technetwork/security-advisory/cpuoct2018-4428296.html
http://www.securityfocus.com/bid/103517	Third Party Advisory VDB Entry
http://www.securitytracker.com/id/1040576	Third Party Advisory VDB Entry
https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=56d5a4bfcaf37fa420aef2bb881aa55e61cf5f2f
https://security.gentoo.org/glsa/201811-21
https://security.netapp.com/advisory/ntap-20180330-0002/	Third Party Advisory
https://www.openssl.org/news/secadv/20180327.txt	Vendor Advisory
https://www.oracle.com/technetwork/security-advisory/cpuapr2019-5072813.html
https://www.oracle.com/technetwork/security-advisory/cpujan2019-5072801.html
https://www.oracle.com/technetwork/security-advisory/cpujul2019-5072835.html
https://www.tenable.com/security/tns-2018-04
https://www.tenable.com/security/tns-2018-06
https://www.tenable.com/security/tns-2018-07

URL

CVE-2018-0733 | Incorrect CRYPTO_memcmp on HP-UX PA-RISC

Exploit prediction scoring system (EPSS) score for CVE-2018-0733

Common vulnerability scoring system (CVSS) metrics for CVE-2018-0733

Weakness enumeration for CVE-2018-0733

OS Trackers for CVE-2018-0733

Affected software / configurations for CVE-2018-0733

References for CVE-2018-0733