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CVE-2026-12528

MEDIUM 5.4

Published 2026-06-17 · Last modified 2026-06-17

A flaw was found in 389 Directory Server in the __aclp__normalize_acltxt() function of aclparse.c. A malformed ACI (Access Control Instruction) string can trigger heap-buffer-overflow writes and reads during ACI parsing. The function fails to validate that the ACI keyword has sufficient length after whitespace stripping, leading to a 1-byte out-of-bounds write and subsequent out-of-bounds reads. An authenticated user with write access to the aci attribute could send a crafted ACI value to silently corrupt heap memory in the directory server process.

NO EXPLOITATION SIGNALS

No known exploitation, public exploit, or elevated probability at this time. Track for changes.

Exploitation likelihood

0.2%chance of exploitation in 30 days · 13th percentile

○ In CISA KEV ○ Public exploit / PoC

Impact if exploited

5.4CVSS 3.1 · MEDIUM

  • ConfidentialityNone
  • IntegrityLow
  • AvailabilityLow

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ⚠Privileges: Requires a low-privilege account
  • ✓User interaction: No user interaction needed
  • ✓Complexity: No special conditions — reliably repeatable

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept & exploit code

Test against your own equipment

curl -s https://vulnpedia.com/cve/CVE-2026-12528/poc.jsonMachine-readable PoC index for this CVE (for automation).

Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-12528/poc.json

Affected

Vendors Red Hat Redhat

Products Red Hat Directory Server 11 Red Hat Directory Server 12 Red Hat Directory Server 13 Red Hat Enterprise Linux 10 Red Hat Enterprise Linux 6 Red Hat Enterprise Linux 7 Red Hat Enterprise Linux 8 Red Hat Enterprise Linux 9 Directory Server 389 Directory Server Enterprise Linux

Weakness (CWE)

  • CWE-787: Out-of-bounds Write

CVSS vector

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

Known Affected Software Configurations

VendorProductVersion range
RedhatDirectory Server11.0
RedhatDirectory Server12.0
RedhatDirectory Server13.0
Redhat389 Directory Server*
RedhatEnterprise Linux7.0
RedhatEnterprise Linux8.0
RedhatEnterprise Linux9.0
RedhatEnterprise Linux10.0

All CVSS metrics

  • MEDIUM 5.4 v3.1 · CNA Primary
    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
  • MEDIUM 5.4 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L

References

Patches & mitigations

Advisories

Sources: NVD · CVE.org · EPSS