CVE-2019-6293

Exp

An issue was discovered in the function mark_beginning_as_normal in nfa.c in flex 2.6.4. There is a stack exhaustion problem caused by the mark_beginning_as_normal function making recursive calls to itself in certain scenarios involving lots of '*' characters. Remote attackers could leverage this vulnerability to cause a denial-of-service.

Published: 2019-01-15 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2019-6293 is rated Exploit Available (59.3/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.45%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2019-6293

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

Exploit prediction scoring system (EPSS) score for CVE-2019-6293

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-11-21 0.21% 0.45% +0.24%
2 2025-11-18 0.45% 0.21% -0.24%
3 2025-08-11 — 0.45% —

Full EPSS history (9 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2019-6293

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.5 3.0 MEDIUM
CVSS:3.0/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]

Weakness enumeration for CVE-2019-6293

OS Trackers for CVE-2019-6293

vendor priority summary link
alpine medium CVE-2019-6293: 1 source package rows (flex); 16 state rows across 10 repos (3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, 3.23-main, edge-main); fixed 16, open 0. https://security.alpinelinux.org/vuln/CVE-2019-6293
debian unimportant CVE-2019-6293 unimportant priority: Debian including 1 source packages (flex), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 5. https://security-tracker.debian.org/tracker/CVE-2019-6293
redhat low — https://access.redhat.com/security/cve/CVE-2019-6293
suse medium — https://www.suse.com/security/cve/CVE-2019-6293/
ubuntu low CVE-2019-6293 low priority: Ubuntu including 1 source packages (flex), 19 status rows across 19 suites (bionic, cosmic, disco, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): ignored 11, needed 6, DNE 1, needs-triage 1. https://ubuntu.com/security/CVE-2019-6293

Affected software / configurations for CVE-2019-6293

Vendor Product Version Raw CPE
westes flex 2.6.4 cpe:2.3:a:westes:flex:2.6.4:*:*:*:*:*:*:*

References for CVE-2019-6293

URL Tags
https://github.com/westes/flex/issues/414 Exploit Third Party Advisory
cvelogic Threat Intelligence