It was found that xorg-x11-server before 1.19.0 including uses memcmp() to check the received MIT cookie against a series of valid cookies.
It was found that xorg-x11-server before 1.19.0 including uses memcmp() to check the received MIT cookie against a series of valid cookies. If the cookie is correct, it is allowed to attach to the Xorg session. Since most memcmp() implementations return after an invalid byte is seen, this causes a time difference between a valid and invalid byte, which could allow an efficient brute force attack.
- Published
- Jul 27, 2018
- Updated
- Jun 16, 2026
- EPSS
- 0.7% · 50th percentile
- CWE
- CWE-385
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Report tools
Action score
28
Monitor
Low priority for now.
- CVSS
- 28 / 40 · 7.0 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.7%
CNA vs NVD score
- NVD
- 7.0
- CNA · redhat
- 5.9
- 1.1 point gap
CVSS:3.0/AV:L/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| x.org | x server | cpe:2.3:a:x.org:x_server |
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- debian debian linux7.0
- x.org x serverup to 1.19.4 inclusive
Versions reported by the vendor
Affected version ranges reported by the assigning authority (redhat). Independent of NVD's CPE analysis and usually ahead of it.
Xorg xorg-x11-server
- 1.19.0affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | xorg-server | before 2:1.19.2-1 | 2:1.19.2-1 |
| Debian:7 | xorg-server | before 2:1.12.4-6+deb7u8 | 2:1.12.4-6+deb7u8 |
| openSUSE:Tumbleweed | xorg-x11-server | before 1.20.13-1.2 | 1.20.13-1.2 |
| SUSE:Linux Enterprise Desktop 12 SP2 | xorg-x11-server | before 7.6_1.18.3-71.1 | 7.6_1.18.3-71.1 |
Same product
x.org: all recordsOther highest-scoring records for the same primary product.
- CVE-2023-6816Xorg-x11-server: heap buffer overflow in devicefocusevent and procxiquerypointer40Plan
- CVE-2007-6427The XInput extension in X.Org Xserver before 1.4.1 allows context-dependent attackers to execute arbitrary code via requests related to byte38Monitor
- CVE-2026-56000xorg-x11-server / xwayland GLX contextTags Use-After-Free in CommonMakeCurrent()36Monitor
- CVE-2026-34002Xorg: xwayland: x.org x server: information disclosure or denial of service via out-of-bounds read in xkb modifier map handling36Monitor
- CVE-2026-34000Xwayland: xorg: x.org x server: information disclosure and denial of service via out-of-bounds read in xkb geometry processing.36Monitor
- CVE-2022-46344A vulnerability was found in X.Org.36Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:xorg-server | 2:1.19.2-1 · Debian:12 | Package registry (OSV) |
| opensuse:xorg-x11-server | 1.20.13-1.2 · openSUSE:Tumbleweed | Package registry (OSV) |
| suse:xorg-x11-server | 7.6_1.18.3-71.1 · SUSE:Linux Enterprise Desktop 12 SP2 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Someone with local access to the system can trigger it.
- A low-privileged account is enough.
- No user action is required.
- Special conditions such as timing or configuration are required.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Local
- Attack complexity
- High
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-385 · Covert Timing ChannelCVSS vector
CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
—
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- www.securityfocus.com/bid/96480
- www.securitytracker.com/id/1037919
- gitlab.freedesktop.org/xorg/xserver/commit/d7ac755f0b618eb1259d93c8a16ec6e39a18627c
- lists.debian.org/debian-lts-announce/2017/11/msg00032.html
- security.gentoo.org/glsa/201704-03
- security.gentoo.org/glsa/201710-30
Vendor advisories and official records. Exploit/PoC links are deliberately left out.