VulnerabilityPublished 13 Jan 2026Updated 19 Oct 2026

CVE-2025-68794: Linux kernel · iomap: adjust read range correctly for non-block-aligned positions

Affects Linux kernelSource CVE Database V5

Not known to be exploited · CVSS 9.8 Critical · fixed in ce20f49ac9194cf81a77f01d1c316d7c17ae753c : patch Linux kernel as a priority.

Data as of 26 Oct 2026, 13:47 UTC

CVSS 3.1 base score

9.8Critical

How severe the flaw is on the 0–10 CVSS scale.

EPSS

0.6% chance of exploitation in 30 days – higher than 52% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers can reliably automate steps 1–4 of the kill chain
Technical impact: Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch

Available – fixed in ce20f49ac9194cf81a77f01d1c316d7c17ae753c, b8c9f25fd84328c5fcc4f70c6d1e8f1d4787eaac, 12053695c8ef5410e8cc6c9ed4c0db9cd9c82b3e +4

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 13 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 9dc55f1389f9569acf9659e58dd836a9c70df217, < ce20f49ac9194cf81a77f01d1c316d7c17ae753c	Fixed in ce20f49ac9194cf81a77f01d1c316d7c17ae753c
LinuxLinux	Affected ≥ 9dc55f1389f9569acf9659e58dd836a9c70df217, < b8c9f25fd84328c5fcc4f70c6d1e8f1d4787eaac	Fixed in b8c9f25fd84328c5fcc4f70c6d1e8f1d4787eaac
LinuxLinux	Affected ≥ 9dc55f1389f9569acf9659e58dd836a9c70df217, < 12053695c8ef5410e8cc6c9ed4c0db9cd9c82b3e	Fixed in 12053695c8ef5410e8cc6c9ed4c0db9cd9c82b3e
LinuxLinux	Affected ≥ 9dc55f1389f9569acf9659e58dd836a9c70df217, < 142194fb21afe964d2d194cab1fc357cbf87e899	Fixed in 142194fb21afe964d2d194cab1fc357cbf87e899
LinuxLinux	Affected ≥ 9dc55f1389f9569acf9659e58dd836a9c70df217, < 275b37a1e5c2c8abd313e8075f6aec9a349f291b	Fixed in 275b37a1e5c2c8abd313e8075f6aec9a349f291b
LinuxLinux	Affected ≥ 9dc55f1389f9569acf9659e58dd836a9c70df217, < 82b60ffbb532d919959702768dca04c3c0500ae5	Fixed in 82b60ffbb532d919959702768dca04c3c0500ae5

AI-suggested

A fix for this vulnerability has been implemented and is available in multiple Linux kernel commits. Users and administrators should update to a patched kernel version that includes these fixes. Since this is not a cloud service, manual patching is required. There are no vendor advisories indicating that no action is required or that the issue is already mitigated.

Description

CVE-2025-68794 is a critical vulnerability in the Linux kernel's iomap subsystem where the function iomap_adjust_read_range() incorrectly handles non-block-aligned read positions. This flaw causes the function to skip too many bytes for uptodate blocks, potentially returning incorrect read positions and lengths, which can lead to underflow and reading beyond the intended memory area. The issue has been fixed in several Linux kernel commits.

Impact

This vulnerability has a CVSS score of 9.8 (critical) with network attack vector, low attack complexity, no privileges required, and no user interaction. It impacts confidentiality, integrity, and availability, potentially allowing an attacker to cause memory corruption or read beyond intended memory boundaries, which could lead to system compromise or denial of service.

Summary

The Linux kernel's iomap_adjust_read_range() function assumed that the position and length parameters were always block-aligned, which is not always true. This incorrect assumption causes the function to skip an excessive number of bytes when all blocks are uptodate, resulting in an underflow of the length and returning a read position beyond the folio boundary. This vulnerability affects Linux kernel version 4.19 and was identified through syzbot testing on the erofs filesystem. The fix adjusts the calculation to correctly account for the block offset when determining how many bytes can be skipped for uptodate blocks.

CWE-190Integer Overflow or Wraparound (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
Requirements
Ensure that all protocols are strictly defined, such that all out-of-bounds behavior can be identified simply, and require strict conformance to the protocol.
Requirements · Language Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V5.4.3 (opens in a new tab)
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
Attack patterns
Forced Integer Overflow (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 12:27 UTC

WeaknessesCWE-190

Technical details

References

Community reviews

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