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CVE-2026-6791· NVD / CVE Program· CNA glibc

Potential stack-based buffer clash during tilde expansion in wordexp

Noroxi assessment

Priority: Monitor (action score 26/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.22% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. Special conditions such as timing or configuration are required.
  • Fixed version: azl3 glibc 2.38-21 on Azure Linux 3.0 Release Notes.

Low priority for now. Upgrade to azl3 glibc 2.38-21 on Azure Linux 3.0 Release Notes or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

When expanding paths that begin with a tilde (~) followed by a username, the internal parse_tilde function extracts the username to determine the user's home directory. The implementation allocates memory for this username directly on the stack using the strndupa macro. Because the size of this allocation was determined by the length of the user-supplied input without any bounds checks, passing an excessively long username e.g. thousands of characters, forces the thread to exhaust its stack space. Thus if an application passes untrusted, attacker-controlled input to the wordexp function, an attacker can trigger a stack clash.

MediumCVSS 6.6 · v4.0—No exploit Fix available
Published
Aug 10, 2026
Updated
Sep 3, 2026
EPSS
0.2% · 11th percentile

Report tools

JSON

Action score

26

Monitor

Low priority for now.

CVSS
26 / 40 · 6.6 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · glibc
6.6
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:L/SA:H/E:U

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (glibc). Independent of NVD's CPE analysis and usually ahead of it.

  • The GNU C Library glibc

    • 2.0 and later · up to and including 2.43affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:10glibcbefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-all-langpacksbefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-benchtestsbefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-commonbefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-develbefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-docbefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-gconv-extrabefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-langpack-aabefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-langpack-afbefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-langpack-agrbefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-langpack-akbefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-langpack-ambefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-langpack-anbefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-langpack-anpbefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-langpack-arbefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-langpack-asbefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-langpack-astbefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-langpack-aycbefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-langpack-azbefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-langpack-bebefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-langpack-bembefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-langpack-berbefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-langpack-bgbefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1
AlmaLinux:10glibc-langpack-bhbbefore 2.39-142.el10_2.alma.12.39-142.el10_2.alma.1

+96

Same product

the gnu c library: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-19499Buffer overflow in strfmon and strfmon_l right-justification padding
    30Monitor
  • CVE-2026-86805AT_SECURE programs may load attacker-controlled code via $ORIGIN
    25Monitor
  • CVE-2025-0395When the assert() function in the GNU C Library versions 2.13 to 2.40 fails, it does not allocate enough space for the assertion failure mes
    24Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2025-8058Jul 23, 2025 · The regcomp function in the GNU C library version from 2.4 to 2.41 is subject to a double free if some previous allocation fails.
    23Monitor
  • Later →CVE-2026-18374Aug 27, 2026 · Passing an effectively empty string to the `,ccs=` syntax extension of the mode argument in the `fopen` function in the GNU C Library versio
    19Monitor
  • Later →CVE-2026-89092Sep 10, 2026 · Stack overflow in nscd due to unbounded alloca use
    16Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
azl3 glibc 2.38-21 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
almalinux:compat-libpthread-nonshared2.28-251.el8_10.43 · AlmaLinux:8Package registry (OSV)
almalinux:glibc2.28-251.el8_10.43 · AlmaLinux:8Package registry (OSV)
almalinux:glibc-all-langpacks2.28-251.el8_10.43 · AlmaLinux:8Package registry (OSV)
almalinux:glibc-benchtests2.28-251.el8_10.43 · AlmaLinux:8Package registry (OSV)
almalinux:glibc-common2.28-251.el8_10.43 · AlmaLinux:8Package registry (OSV)
almalinux:glibc-devel2.28-251.el8_10.43 · AlmaLinux:8Package registry (OSV)
almalinux:glibc-doc2.28-251.el8_10.43 · AlmaLinux:8Package registry (OSV)
almalinux:glibc-gconv-extra2.28-251.el8_10.43 · AlmaLinux:8Package registry (OSV)
almalinux:glibc-headers2.28-251.el8_10.43 · AlmaLinux:8Package registry (OSV)
almalinux:glibc-langpack-aa2.28-251.el8_10.43 · AlmaLinux:8Package registry (OSV)
almalinux:glibc-langpack-af2.28-251.el8_10.43 · AlmaLinux:8Package registry (OSV)
almalinux:glibc-langpack-agr2.28-251.el8_10.43 · AlmaLinux:8Package registry (OSV)
debian:glibc2.43-3 · Debian:14Package registry (OSV)
opensuse:glibc2.44-1.1 · openSUSE:TumbleweedPackage registry (OSV)
opensuse:glibc-cross-aarch64-src2.40-160000.7.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:glibc-cross-ppc64le-src2.40-160000.7.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:glibc-cross-riscv64-src2.40-160000.7.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:glibc-cross-s390x-src2.40-160000.7.1 · openSUSE:Leap 16.0Package registry (OSV)
red hat:compat-libpthread-nonshared0:2.43-8.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:glibc0:2.43-8.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:glibc-all-langpacks0:2.43-8.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:glibc-benchtests0:2.43-8.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:glibc-common0:2.43-8.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:glibc-devel0:2.43-8.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:glibc-doc0:2.43-8.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:glibc-gconv-extra0:2.43-8.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:glibc-langpack-aa0:2.43-8.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:glibc-langpack-af0:2.43-8.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:glibc-langpack-agr0:2.43-8.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)

+3

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.

EPSS, last 120 days

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.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-1954235 days apartStack-based out-of-bounds write in tdelete during tree rebalancing
    22Monitor
  • CVE-2026-9581843 days apartAT_SECURE program buffer overflow via $ORIGIN processing
    14Monitor

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

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
X

Weakness class (CWE)

CWE-121 · Stack-based Buffer Overflow

CVSS vector

CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:L/SA:H/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records