Linux: Integer Underflow (Wrap or Wraparound)
CVE-2026-53176 is a critical-severity integer underflow (wrap or wraparound) vulnerability in Linux, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 75ee6e4aa096aa9e7b2dd5c8ff98356e30aceefb, e8a013c0c3ca2f6708341a56612a3f6d6921620a, bd22740d7f14cb1c0289444cfd2c8d2938667c1d as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.76% chance of exploitation within 30 days, higher than 56% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Linux to 75ee6e4aa096aa9e7b2dd5c8ff98356e30aceefb or e8a013c0c3ca2f6708341a56612a3f6d6921620a or bd22740d7f14cb1c0289444cfd2c8d2938667c1d or c1234229399f4af12c553b1b0ffd978eeba65548, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.259 or 5.15.210 or 6.1.176 or 6.6.143, whichever matches your release line, or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | b8d26b3be8b33682cf163274ed07479a70554633 up to, but not including, 75ee6e4aa096aa9e7b2dd5c8ff98356e30aceefb; b8d26b3be8b33682cf163274ed07479a70554633 up to, but not including, e8a013c0c3ca2f6708341a56612a3f6d6921620a; b8d26b3be8b33682cf163274ed07479a70554633 up to, but not including, bd22740d7f14cb1c0289444cfd2c8d2938667c1d; b8d26b3be8b33682cf163274ed07479a70554633 up to, but not including, c1234229399f4af12c553b1b0ffd978eeba65548; b8d26b3be8b33682cf163274ed07479a70554633 up to, but not including, c5584e089b5af7b3bf8bd5e8ca0560cbf32b0a47; b8d26b3be8b33682cf163274ed07479a70554633 up to, but not including, df422fd273c96c2ee5beb80fc21adc8c70c29260; b8d26b3be8b33682cf163274ed07479a70554633 up to, but not including, 1ca40b243277c9e88be5e00bd3e083f71aefb93e; b8d26b3be8b33682cf163274ed07479a70554633 up to, but not including, 29e7b925ae6df64894e82ab6419994dc25580a8a; and 1 more ranges | 75ee6e4aa096aa9e7b2dd5c8ff98356e30aceefb, e8a013c0c3ca2f6708341a56612a3f6d6921620a, bd22740d7f14cb1c0289444cfd2c8d2938667c1d, c1234229399f4af12c553b1b0ffd978eeba65548, c5584e089b5af7b3bf8bd5e8ca0560cbf32b0a47, df422fd273c96c2ee5beb80fc21adc8c70c29260 |
| Red Hat | Red Hat Enterprise Linux 10 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 8 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 9 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 6 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 7 | Not specified in the record | Not stated |
| Linux | Linux Kernel | 3.10 up to, but not including, 5.10.259; 5.11 up to, but not including, 5.15.210; 5.16 up to, but not including, 6.1.176; 6.2 up to, but not including, 6.6.143; 6.7 up to, but not including, 6.12.94; 6.13 up to, but not including, 6.18.36; 6.19 up to, but not including, 7.0.13; 7.1 | 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.94, 6.18.36 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 9.8 | Critical | CNA |
| CVSS 3.1 | 6.5 | Medium | CNA |
Official description
In the Linux kernel, the following vulnerability has been resolved: IB/isert: Reject login PDUs shorter than ISER_HEADERS_LEN In drivers/infiniband/ulp/isert/ib_isert.c, isert_login_recv_done() computes the login request payload length as wc->byte_len minus ISER_HEADERS_LEN with no lower bound, and login_req_len is a signed int. A remote iSER initiator can post a login Send work request carrying fewer than ISER_HEADERS_LEN (76) bytes, so the subtraction underflows and login_req_len becomes negative. isert_rx_login_req() then reads that negative length back into a signed int, takes size = min(rx_buflen, MAX_KEY_VALUE_PAIRS), and because the min() is signed it keeps the negative value; the value is then passed as the memcpy() length and sign-extended to a multi-gigabyte size_t. The copy into the 8192-byte login->req_buf runs far out of bounds and faults, crashing the target node. The login phase precedes iSCSI authentication, so no credentials are required to reach this path. Reject any login PDU shorter than ISER_HEADERS_LEN before the subtraction, mirroring the existing early return on a failed work completion, so login_req_len can never go negative. The upper bound was already safe: a posted login buffer cannot deliver more than ISER_RX_PAYLOAD_SIZE, so the difference stays at or below MAX_KEY_VALUE_PAIRS and the existing min() clamps it; only the missing lower bound needs to be added.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Integer Underflow (Wrap or Wraparound)
The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.
More Integer Underflow (Wrap or Wraparound) vulnerabilities (CWE-191)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/1ca40b243277c9e88be5e00bd3e083f71aefb93e
- git.kernel.org/stable/c/29e7b925ae6df64894e82ab6419994dc25580a8a
- git.kernel.org/stable/c/75ee6e4aa096aa9e7b2dd5c8ff98356e30aceefb
- git.kernel.org/stable/c/bd22740d7f14cb1c0289444cfd2c8d2938667c1d
- git.kernel.org/stable/c/c1234229399f4af12c553b1b0ffd978eeba65548
- git.kernel.org/stable/c/c5584e089b5af7b3bf8bd5e8ca0560cbf32b0a47
- git.kernel.org/stable/c/df422fd273c96c2ee5beb80fc21adc8c70c29260
- git.kernel.org/stable/c/e8a013c0c3ca2f6708341a56612a3f6d6921620a
Third-party and government advisories
- access.redhat.com/security/cve/CVE-2026-53176Third Party Advisory
- bugzilla.redhat.com/show_bug.cgi?id=2492741Issue Tracking, Third Party Advisory
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-53176.jsonThird Party Advisory
Other references
Recent Integer Underflow (Wrap or Wraparound) vulnerabilities
- 8.1 High severity
- 7.8 High severity
- 7.8 High severity
- 9.1 Critical severity
- 7.5 High severity
- 7.5 High severity
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