CVE-2018-21232 [Medium] | Security Vulnerability in Re2c

CVE-2018-21232 is rated High Exploit Risk (62.6/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 1.43%). 1 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +1.33% over the last day, indicating growing attacker interest. Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

EDB-ID	Source	Kind	Published	Link
—	nvd_ref	exploit_tag		Exploit-DB ↗

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Published

Link

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#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.10%	1.43%	+1.33%
2	2025-11-21	0.20%	0.10%	-0.10%
3	2025-11-18	—	0.20%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.10%

1.43%

+1.33%

2025-11-21

0.20%

0.10%

-0.10%

2025-11-18

—

0.20%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
5.5	3.1	MEDIUM	`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H` Click to expand Attack vector (AV:L) They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:R) A real person has to do something—click, install, enable—otherwise it doesn’t land. 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:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	1.8	3.6	[email protected]
4.3	2.0	MEDIUM	`AV:N/AC:M/Au:N/C:N/I:N/A:P` 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:N) No integrity impact. Availability impact (A:P) Partial availability impact.	8.6	2.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

5.5

3.1

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H Click to expand

Attack vector (AV:L): They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R): A real person has to do something—click, install, enable—otherwise it doesn’t land.
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:N): Data isn’t meaningfully altered or forged.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

1.8

3.6

[email protected]

4.3

2.0

MEDIUM

AV:N/AC:M/Au:N/C:N/I:N/A:P 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:N): No integrity impact.
Availability impact (A:P): Partial availability impact.

8.6

2.9

[email protected]

OS Trackers for CVE-2018-21232

vendor	priority	summary	link
`alpine`	medium	CVE-2018-21232: 1 source package rows (re2c); 7 state rows across 7 repos (3.11-main, 3.12-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 0, open 7.	https://security.alpinelinux.org/vuln/CVE-2018-21232
`debian`	unimportant	CVE-2018-21232 unimportant priority: Debian including 1 source packages (re2c), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 5.	https://security-tracker.debian.org/tracker/CVE-2018-21232
`gentoo`	normal	CVE-2018-21232: 1 GLSA(s) (202408-16), 1 atom(s) (dev-util/re2c); latest impact normal.	https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2018-21232
`redhat`	low	—	https://access.redhat.com/security/cve/CVE-2018-21232
`ubuntu`	low	CVE-2018-21232 low priority: Ubuntu including 1 source packages (re2c), 17 status rows across 17 suites (bionic, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): ignored 9, needed 5, not-affected 2, released 1.	https://ubuntu.com/security/CVE-2018-21232

Affected software / configurations for CVE-2018-21232

Vendor	Product	Version	Raw CPE
re2c	re2c	< 2.0	cpe:2.3:a:re2c:re2c::::::::

References for CVE-2018-21232

URL	Tags
http://www.openwall.com/lists/oss-security/2020/05/14/4
https://github.com/skvadrik/re2c/issues/219	Exploit Patch Third Party Advisory
https://www.openwall.com/lists/oss-security/2020/04/27/2	Mailing List Third Party Advisory

URL

CVE-2018-21232

Public exploit references (Exploit-DB) for CVE-2018-21232

Exploit prediction scoring system (EPSS) score for CVE-2018-21232

Common vulnerability scoring system (CVSS) metrics for CVE-2018-21232

Weakness enumeration for CVE-2018-21232

OS Trackers for CVE-2018-21232

Affected software / configurations for CVE-2018-21232

References for CVE-2018-21232