Reports
Weekly WebKit security reports.
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W40
12 picks from 686 commits 2026-10-03 – 09 2 security 10 dev v1.11.0
A WebGL2 page could get the GPU process to paint stale heap where its frame belonged.; A compromised renderer could put any site's name on the system credential chooser.; Feed WebCodecs a 10-bit frame and its encoder ships uninitialized heap as video.
UninitializedMemory1AuthBypass1 -
W39
16 picks from 620 commits 2026-09-26 – 10-02 6 security 10 dev v1.11.0
A compromised renderer could take another navigation's response just by naming it.; CSP blocked the style attribute, unless it was parsed somewhere with no policy.; Under Site Isolation, the UI process relayed postMessage origins it never checked.
LogicError3Other1UAF1CrossOrigin1+3 -
W38
16 picks from 518 commits 2026-09-19 – 25 6 security 10 dev v1.10.1
Two iframes, two Set prototypes, and the compiled code watching the wrong one.; Instruction selection sank an atomic past memory.grow, onto memory already freed.; The canvas save stack hit its cap, and the cap stopped being a resource limit.
Other4LogicError2CrossOrigin2AuthBypass1+3 -
W37
16 picks from 453 commits 2026-09-12 – 18 6 security 10 dev v1.9.0
A cookie check that only asked whether the message agreed with itself.; Renderer bytes reached the host app's full codec set — PSD, RAW, EXR.; The blocklist compared strings while AppKit compared identities.
LogicError4UAF3Race3SandboxEscape2+2 -
W36
15 picks from 427 commits 2026-09-05 – 11 6 security 9 dev v1.9.0
The callback kept the speech engine alive and let its listener die.; The history check read one node and vouched for the entire tree.; A queue that quietly declines work picks the thread your destructor runs on.
UAF3IntegerOverflow2LogicError1OOB1+3 -
W35
16 picks from 462 commits 2026-08-29 – 09-04 6 security 10 dev v1.9.0
Constant folding deleted the one check the rest of the compile had already spent; A number crossed the IPC boundary and came back out as a pointer; The filter ran first, then the worklist quietly put the candidates back
OOB8Race6TypeConfusion4UAF3+6 -
W34
16 picks from 454 commits 2026-08-22 – 28 6 security 10 dev v1.9.0
A prior fix taught one `End` handler to widen. The parser has two.; DFG liveness is a union over CFG successors. A catch handler isn't one.; A cross-instance tail call installs the callee's bounds limit, then overwrites it.
UAF10TypeConfusion10OOB6IntegerOverflow5+15 -
W33
15 picks from 422 commits 2026-08-15 – 21 5 security 10 dev v1.7.0
The detach that guarantees no compiled code survives missed one cache.; The APNG geometry check authorised the compositing loop, not the transform after it.; The privileged process took the sandboxed one's word for a buffer's shape.
OOB2CrossOrigin1Race1UAF1 -
W32
7 picks from 384 commits 2026-08-08 – 14 6 security 1 dev v1.3.3
Sixteen storage handlers took an integer as proof you owned the file.; Another site's cache will happily serve back what you wrote into it.; A shadow-DOM cache that outlived the table it was stored inside.
AuthBypass2CrossOrigin2Race2TypeConfusion2+5 -
W31
8 picks from 470 commits 2026-08-01 – 07 1 security 7 dev v1.3.0
Three WebAuthn replies came back on a queue WebKit didn't choose.; Two array opcodes shared one case label in JSC's write-barrier phase.; The memory64 check that only looked at the memory it was holding.
IntegerOverflow3UAF2Race1TypeConfusion1+1 -
W30
2 picks from 452 commits 2026-07-25 – 31 2 dev v1.3.0
An ordinary indexOf call writes one int past a heap search table.; Wasm table linking checked type, size, and max — everything but the address width.
TypeConfusion1OOB1 -
W29
5 picks from 468 commits 2026-07-18 – 24 4 security 1 dev v1.2.0
The hash check that ran before the script even existed.; A hot defineProperty fold kept a shape but dropped the check it was an object.; A recorded font stays safe on one thread — until a canvas hands it to two.
TypeConfusion2MemoryCorruption1LogicError1CrossOrigin1 -
W28
5 picks from 488 commits 2026-07-11 – 17 3 security 2 dev v1.2.0
The JIT proved a broad type and treated it as proof of the exact one.; A lock refactor let a shared object's last reference escape the lock.; The privileged process trusted the sandbox to say the user tapped.
UAF3AuthBypass1TypeConfusion1 -
W27
6 picks from 447 commits 2026-07-04 – 10 6 security v1.3.2
The per-thread isolation held at every level except the one that made levels.; Overwriting a callback was a free, and a real-time thread was inside it.; Three code paths dropped the pointer. Only the destructor remembered to detach.
UAF4AuthBypass3Other2 -
W26
8 picks from 557 commits 2026-06-27 – 07-03 6 security 2 dev v1.7.0
Omit one argument and the promise-pair bindings hand you an exception cell.; A buffer you can free between assigning it and pressing play.; A compromised renderer names a file it can't read, and Safari hands it back.
UAF41Race20AuthBypass17LogicError15+61 -
W25
6 picks 2026-06-20 – 26 6 security v1.3.2
The UI process asked the sandbox which site it was talking to.; Two threads, one easing curve, and a reference count that couldn't count.; A frame ID is a name, not a permission — the pasteboard disagreed.
CrossOrigin2AuthBypass1Other1UAF1+1 -
W24
7 picks 2026-06-13 – 19 6 security 1 dev v1.3.3
Two of four sibling access types never told the collector what they held.; The literal parser knew __proto__ could run script, and guarded the wrong thing.; The dialog handed back a return value from memory the page just freed.
UAF6Race5TypeConfusion3AuthBypass3+7 -
W23
8 picks 2026-06-06 – 12 6 security 2 dev v1.3.3
Closing a page freed the <html> element out from under its own shadow trees.; A scope guard that pinned the string cell but not the bytes you were reading; Streams' pipeTo checked for a fake promise with a cast that never fails
UAF9OOB5Race5CrossOrigin4+13 -
W22
9 picks 2026-05-30 – 06-05 6 security 3 dev v1.3.3
The CORS policy took a detour through the process it was written to contain.; The eval cache kept a raw pointer that nothing was keeping alive.; The array that came back from an OSR exit disagreed with itself about its layout.
CrossOrigin6Other5UAF4LogicError3+10 -
W21
6 picks 2026-05-23 – 29 6 security v1.3.3
B3 was right that the value was dead — the collector agreed, and freed it.; The DFG certified a property absent from an object that owned it outright.; An IC exit undid a stack adjustment that had never happened.
UAF10OOB5AuthBypass5LogicError5+17