CVE Intelligence
Medium Memory corruption

CVE-2025-0677 — Grub2: ufs: integer overflow may lead to heap based out-of-bounds write when handling symlinks

A flaw was found in grub2. When performing a symlink lookup, the grub's UFS module checks the inode's data size to allocate the internal buffer to read the file content, however, it fails to check if the symlink data size has overflown. When this occurs, grub_malloc() may be called with a smaller value than needed. When further reading the data from the disk into the buffer, the grub_ufs_lookup_symlink() function will write past the end of the allocated size. An attack can leverage this by crafting a malicious filesystem, and as a result, it will corrupt data stored in the heap, allowing for arbitrary code execution used to by-pass secure boot mechanisms.

Published Feb 19, 2025 · Updated Oct 21, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: redhat

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.3% (30-day exploitation probability)+4
  • Technical severity (medium)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.33%
ahead of 25% of scored CVEs · Oct 22, 2026
Affects
Red Hat
Red Hat Enterprise Linux 10 and 2 more
CVSS base
6.4
Medium · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Total
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Red Hat Red Hat Enterprise Linux 10, Red Hat Red Hat Enterprise Linux 9, Red Hat Red Hat OpenShift Container Platform 4).
  2. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  3. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Red Hat Red Hat Enterprise Linux 10 versions not specified by the source Vulnerable CVE Program (cve.org) e CISA ADP
Red Hat Red Hat Enterprise Linux 9 versions not specified by the source Vulnerable CVE Program (cve.org) e CISA ADP
Red Hat Red Hat OpenShift Container Platform 4 versions not specified by the source Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Local
Attack complexity
High
Privileges required
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
6.4 CVSS 3.1 Medium 0.5 5.9 secalert@redhat.com via NIST National Vulnerability Database
6.4 CVSS 3.1 Medium — — GitHub, Inc. via GitHub Security Advisories
6.4 CVSS 3.1 Medium — — redhat via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H (score shown at the top: secalert@redhat.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-787 · Out-of-bounds Write

Other CVEs with this weakness →

EPSS over time FIRST

Oct 21, 2026 → Oct 22, 2026 · 2 reading(s) · max 0.33%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
  • Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
endpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · red hat/red hat openshift container platform 4
    Oct 21, 2026 · CVE Program (cve.org) e CISA ADP
  • Affected products added · red hat/red hat enterprise linux 10, red hat/red hat enterprise linux 9
    Oct 21, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 21, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 21, 2026
  • CVSS changed · 6.4
    Oct 21, 2026 · NIST National Vulnerability Database
  • Source status changed · → Deferred
    Oct 21, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 21, 2026 · NIST National Vulnerability Database
  • 2025
  • CVE published
    Feb 19, 2025 · redhat

Source activity

Repeated readings are counted rather than listed.

  • 1× References added · Oct 21, 2026 – Oct 21, 2026
  • 1× Official description updated · Oct 21, 2026 – Oct 21, 2026

References

7 on the record

Elsewhere on this site

Red Hat
every CVE for this vendor
Memory corruption
same class
CWE-787
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-115486 Open-iscsi: open-iscsi: ipv6 neighbor discovery missing option length validation in iscsiuio allows arp table poisoning 17h
  • CVE-2026-115485 Open-iscsi: open-iscsi: dhcpv6 vendor option strlen heap out-of-bounds read and 1-byte write in iscsiuio 17h
  • CVE-2026-115484 Open-iscsi: open-iscsi: dhcpv4 option parser heap out-of-bounds read in iscsiuio parse_msg 17h
  • CVE-2026-115449 Libslirp: libslirp: icmp echo reply length desynchronization leaks host ip to guest 20h
  • CVE-2026-115221 Ipa: freeipa: freeipa uses subject cn as proof of certificate ownership 20h
  • CVE-2026-115424 Oc: oc: symlink/hardlink target validation bypass in oc image extract allows file write outside destination 20h

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No fixed version, patch or mitigation documented.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2025-0677 is "Grub2: ufs: integer overflow may lead to heap based out-of-bounds write when handling symlinks", rated Medium. It affects Red Hat Enterprise Linux 10 (Red Hat); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 6.4 describes technical severity. EPSS 0.33% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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