Linux: Out-of-bounds Write
CVE-2026-43500 is a high-severity out-of-bounds write vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 7c504ffab3efce8f7e4f463b314ae31030bdf18b, 3711382a77342a9a1c3d2e7330dcfc7ea927f568, 3eae0f4f9f7206a4801efa5e0235c25bbd5a412c 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 94.1% chance of exploitation within 30 days, which is in the top 0.15% of all scored CVEs.
Exploitation in the next 30 days is more likely than not, according to EPSS.
What to do
- Update Linux to 7c504ffab3efce8f7e4f463b314ae31030bdf18b or 3711382a77342a9a1c3d2e7330dcfc7ea927f568 or 3eae0f4f9f7206a4801efa5e0235c25bbd5a412c or d45179f8795222ce858770dc619abe51f9d24411, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.18.29 or 7.0.6, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | d0d5c0cd1e711c98703f3544c1e6fc1372898de5 up to, but not including, 7c504ffab3efce8f7e4f463b314ae31030bdf18b; d0d5c0cd1e711c98703f3544c1e6fc1372898de5 up to, but not including, 3711382a77342a9a1c3d2e7330dcfc7ea927f568; d0d5c0cd1e711c98703f3544c1e6fc1372898de5 up to, but not including, 3eae0f4f9f7206a4801efa5e0235c25bbd5a412c; d0d5c0cd1e711c98703f3544c1e6fc1372898de5 up to, but not including, d45179f8795222ce858770dc619abe51f9d24411; d0d5c0cd1e711c98703f3544c1e6fc1372898de5 up to, but not including, aa54b1d27fe0c2b78e664a34fd0fdf7cd1960d71; 5.3 | 7c504ffab3efce8f7e4f463b314ae31030bdf18b, 3711382a77342a9a1c3d2e7330dcfc7ea927f568, 3eae0f4f9f7206a4801efa5e0235c25bbd5a412c, d45179f8795222ce858770dc619abe51f9d24411, aa54b1d27fe0c2b78e664a34fd0fdf7cd1960d71 |
| Red Hat | Red Hat Enterprise Linux 10 | 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 |
| 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 OpenShift Container Platform 4 | Not specified in the record | Not stated |
| Linux | Linux Kernel | after 5.3 up to, but not including, 6.18.29; 6.19 up to, but not including, 7.0.6; 5.3; 7.1 | 6.18.29, 7.0.6 |
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
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- 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:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | NVD |
| CVSS 3.1 | 7.8 | High | CISA (ADP) |
| CVSS 3.1 | 7.8 | High | CNA |
Official description
In the Linux kernel, the following vulnerability has been resolved: rxrpc: Also unshare DATA/RESPONSE packets when paged frags are present The DATA-packet handler in rxrpc_input_call_event() and the RESPONSE handler in rxrpc_verify_response() copy the skb to a linear one before calling into the security ops only when skb_cloned() is true. An skb that is not cloned but still carries externally-owned paged fragments (e.g. SKBFL_SHARED_FRAG set by splice() into a UDP socket via __ip_append_data, or a chained skb_has_frag_list()) falls through to the in-place decryption path, which binds the frag pages directly into the AEAD/skcipher SGL via skb_to_sgvec(). Extend the gate to also unshare when skb_has_frag_list() or skb_has_shared_frag() is true. This catches the splice-loopback vector and other externally-shared frag sources while preserving the zero-copy fast path for skbs whose frags are kernel-private (e.g. NIC page_pool RX, GRO). The OOM/trace handling already in place is reused.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Write
The product writes data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
- Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other references
- git.kernel.org/stable/c/3711382a77342a9a1c3d2e7330dcfc7ea927f568
- git.kernel.org/stable/c/7c504ffab3efce8f7e4f463b314ae31030bdf18b
- access.redhat.com/security/cve/CVE-2026-43500
- bugzilla.redhat.com/show_bug.cgi?id=2468273
- github.com/V4bel/dirtyfrag
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-43500.json
Recent Out-of-bounds Write vulnerabilities
- 7.3 High severity
- 9.8 Critical severity
- 8.1 High severity
- 7.8 High severity
- 7.8 High severity
- 8.8 High severity
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