CVE-2019-18634

In Sudo before 1.8.26, if pwfeedback is enabled in /etc/sudoers, users can trigger a stack-based buffer overflow in the privileged sudo process. (pwfeedback is a default setting in Linux Mint and elementary OS; however, it is NOT the default for upstream and many other packages, and would exist only if enabled by an administrator.) The attacker needs to deliver a long string to the stdin of getln() in tgetpass.c.

CVSS: 7.8High
Exploited in the wild: Not knownPublic exploit code; not in CISA KEV
EPSS: 19.3%chance of exploitation in the next 30 daystop 3% of scored CVEsFIRST score of 11 Nov 2026
Fix: Patch availablesee the advisories in the references
Published: 29 Jan 2020analysed here 12 Nov 2026

Summary

Triage

Attack surface: Server-side
Exploitable: At runtime
Attack vector: local
Weakness: CWE-787 Out-of-Bounds Write
Can a WAF block it?: No. See why

The summary, impact and action text on this page are written by our AI analysis pipeline, or taken from the NVD description when a CVE was imported from NVD. They are not the vendor's wording: check them against the sources. A longer AI executive summary and technical analysis are generated for signed-in accounts on the Max plan.

Affected products

Products named in our analysis

sudo_project:sudo
debian:debian_linux

Fix and mitigation

WAF and other mitigations

Can a WAF block it? No. The attack needs local access to the machine, so a WAF is not on its path.

Also consider: patch

Based on the attack vector (local or physical access). We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.

Remediation steps (AI-written)

Step-by-step remediation is generated for accounts on the Max plan, for CVEs that match a technology in their stack. Add this technology to your stack to see the fix checklist.

Exploitation evidence

CISA KEV catalog: Not listed as of our last sync.
Public exploit code: Yes: 2 on Exploit-DB · 14 GitHub proofs of concept

Exploit-DB

Sudo 1.8.25p - 'pwfeedback' Buffer Overflowlocal, 6 Feb 2020
Sudo 1.8.25p - 'pwfeedback' Buffer Overflow (PoC)dos, 4 Feb 2020

GitHub proofs of concept

saleemrashid/sudo-cve-2019-18634239 stars
Plazmaz/CVE-2019-1863459 stars
aesophor/CVE-2019-186345 stars
chanbakjsd/CVE-2019-186343 stars

and 10 more repositories

Listed so you can judge urgency, not as a recommendation to run anything. GitHub “proofs of concept” are unvetted: some are fake or carry malware. Exploit-DB marks the entries its staff verified.

Timeline

29 Jan 2020Published
4 Feb 2020First public exploit or proof of concept5 days later
5 Aug 2024CVE record last updated1,644 days (about 5 years) later
12 Nov 2026Analysed by vulneraibility.com829 days (about 2 years) later

CVSS vector

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

Metric	Value	What it means
Attack vector	LocalLocal access required (shell, logged-in user).	Local access required (shell, logged-in user).
Attack complexity	LowRepeatable attack, no special conditions.	Repeatable attack, no special conditions.
Privileges required	LowThe attacker needs basic user privileges.	The attacker needs basic user privileges.
User interaction	NoneNo victim action needed.	No victim action needed.
Scope	UnchangedImpact stays within the vulnerable component.	Impact stays within the vulnerable component.
Confidentiality	HighTotal data disclosure possible.	Total data disclosure possible.
Integrity	HighComplete modification possible.	Complete modification possible.
Availability	HighFull outage possible.	Full outage possible.

Common questions

Is CVE-2019-18634 being exploited?

Not confirmed. CVE-2019-18634 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 19% probability of exploitation in the next 30 days.

How severe is CVE-2019-18634?

CVE-2019-18634 is rated High with a CVSS score of 7.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.

Is there a patch for CVE-2019-18634?

Yes. A fix has been recorded for CVE-2019-18634. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.

What does CVE-2019-18634 affect?

CVE-2019-18634 affects sudo_project:sudo, debian:debian_linux. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.

Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.

References

NVD CVE.org CVE Details Source

26 references in the CVE record, grouped by the tags the record gives them.

Advisories (11)

debian.org /security/2020/dsa-4614
usn.ubuntu.com /4263-1/
usn.ubuntu.com /4263-2/
access.redhat.com /errata/RHSA-2020:0487
access.redhat.com /errata/RHSA-2020:0509
access.redhat.com /errata/RHSA-2020:0540

Show 5 more

lists.opensuse.org /opensuse-security-announce/2020-02/msg00029.html
lists.fedoraproject.org /archives/list/package-announce%40lists.fedoraproject.org/message/IY6DZ7WMDKU4ZD
access.redhat.com /errata/RHSA-2020:0726
security.gentoo.org /glsa/202003-12
lists.fedoraproject.org /archives/list/package-announce%40lists.fedoraproject.org/message/I6TKF36KOQUVJN

Where the data on this page comes from

CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
NVD: CVSS and CPE data
FIRST EPSS: exploit probability and percentile
Exploit-DB: published exploits
PoC-in-GitHub: GitHub repositories that claim a proof of concept

Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.

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