um: vector: fix use-after-free in vector_mmsg_rx()
When vector_mmsg_rx() discards a packet whose overlay header fails
verify_header(), it frees the skb and continues the loop:
if (header_check < 0) {
dev_kfree_skb_irq(skb);
vp->estats.rx_encaps_errors++;
continue;
}
The normal and short-packet paths fall through to the bottom of the
loop body, which clears the consumed slot and advances the cursors:
(*skbuff_vector) = NULL;
mmsg_vector++;
skbuff_vector++;
The verify_header() < 0 path skips that via continue, so the freed skb
is left in skbuff_vector[] and the cursors do not advance. The next
iteration reads the same slot, gets the freed skb, and frees it again,
producing a refcount underflow / use-after-free in the RX path.
Discard the slot the same way the other paths do before continuing.
Only transports whose verify_header() can return negative are affected:
GRE and L2TPv3 do so on a cookie/session-id mismatch (raw/tap do not),
so any peer on such a transport can trigger it without authentication.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||||||||||||||||||||
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| Linux | Linux | unaffected |
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| Linux | Linux | affected |
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No data.
No data.
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| Vendors | Products |
|---|---|
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Linux
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Linux Kernel
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No advisories yet.
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
Wed, 19 Aug 2026 16:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
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Mon, 17 Aug 2026 12:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-416 |
Mon, 17 Aug 2026 06:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
cvssV3_1
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Sat, 15 Aug 2026 18:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-416 |
Sat, 15 Aug 2026 12:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: um: vector: fix use-after-free in vector_mmsg_rx() When vector_mmsg_rx() discards a packet whose overlay header fails verify_header(), it frees the skb and continues the loop: if (header_check < 0) { dev_kfree_skb_irq(skb); vp->estats.rx_encaps_errors++; continue; } The normal and short-packet paths fall through to the bottom of the loop body, which clears the consumed slot and advances the cursors: (*skbuff_vector) = NULL; mmsg_vector++; skbuff_vector++; The verify_header() < 0 path skips that via continue, so the freed skb is left in skbuff_vector[] and the cursors do not advance. The next iteration reads the same slot, gets the freed skb, and frees it again, producing a refcount underflow / use-after-free in the RX path. Discard the slot the same way the other paths do before continuing. Only transports whose verify_header() can return negative are affected: GRE and L2TPv3 do so on a cookie/session-id mismatch (raw/tap do not), so any peer on such a transport can trigger it without authentication. | |
| Title | um: vector: fix use-after-free in vector_mmsg_rx() | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
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Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-08-19T16:37:30.555Z
Reserved: 2026-08-15T05:44:03.903Z
Link: CVE-2026-74478
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-08-15T13:17:52.600
Modified: 2026-08-19T17:21:04.947
Link: CVE-2026-74478
Redhat
No data.
OpenCVE Enrichment
Updated: 2026-08-17T14:15:04Z
No weakness.