'SameSite' cookie attribute

Same-site cookies ("First-Party-Only" or "First-Party") allow servers to mitigate the risk of CSRF and information leakage attacks by asserting that a particular cookie should only be sent with requests initiated from the same registrable domain.

Spec	https://tools.ietf.org/html/draft-ietf-httpbis-rfc6265bis-07
Status	Other

IE	Edge	Firefox	Chrome	Safari	Opera
			98 ⁽³⁾
		95	97 ⁽³⁾
		94	96 ⁽³⁾	TP
11 ^(1,2)	95 ⁽³⁾	93	95 ⁽³⁾	15	80 ⁽³⁾
10	94 ⁽³⁾	92	94 ⁽³⁾	14.1	79 ⁽³⁾
9	93 ⁽³⁾	91	93 ⁽³⁾	14 ⁽⁵⁾	78 ⁽³⁾
8	92 ⁽³⁾	90	92 ⁽³⁾	13.1 ^(4,5)	77 ⁽³⁾
Show all
7	91 ⁽³⁾	89	91 ⁽³⁾	13 ^(4,5)	76 ⁽³⁾
6	90 ⁽³⁾	88	90 ⁽³⁾	12.1 ^(4,5)	75 ⁽³⁾
5.5	89 ⁽³⁾	87	89 ⁽³⁾	12 ^(4,5)	74 ⁽³⁾
	88 ⁽³⁾	86	88 ⁽³⁾	11.1	73 ⁽³⁾
	87 ⁽³⁾	85	87 ⁽³⁾	11	72 ⁽³⁾
	86 ⁽³⁾	84	86 ⁽³⁾	10.1	71 ⁽³⁾
	85	83	85 ⁽³⁾	10	70
	84	82	84 ⁽³⁾	9.1	69
	83	81	83 ⁽³⁾	9	68
	81	80	81 ⁽³⁾	8	67
	80	79	80 ⁽³⁾	7.1	66
	79	78	79	7	65
	18	77	78	6.1	64
	17 ⁽¹⁾	76	77	6	63
	16 ⁽¹⁾	75	76	5.1	62
	15	74	75	5	60
	14	73	74	4	58
	13	72	73	3.2	57
	12	71	72	3.1	56
		70	71		55
		69	70		54
		68	69		53
		67	68		52
		66	67		51
		65	66		50
		64	65		49
		63	64		48
		62	63		47
		61	62		46
		60	61		45
		59	60		44
		58	59		43
		57	58		42
		56	57		41
		55	56		40
		54	55		39
		53	54		38
		52	53		37
		51	52		36
		50	51		35
		49	50		34
		48	49		33
		47	48		32
		46	47		31
		45	46		30
		44	45		29
		43	44		28
		42	43		27
		41	42		26
		40	41		25
		39	40		24
		38	39		23
		37	38		22
		36	37		21
		35	36		20
		34	35		19
		33	34		18
		32	33		17
		31	32		16
		30	31		15
		29	30		12.1
		28	29		12
		27	28		11.6
		26	27		11.5
		25	26		11.1
		24	25		11
		23	24		10.6
		22	23		10.5
		21	22		10.0-10.1
		20	21		9.5-9.6
		19	20		9
		18	19
		17	18
		16	17
		15	16
		14	15
		13	14
		12	13
		11	12
		10	11
		9	10
		8	9
		7	8
		6	7
		5	6
		4	5
		3.6	4
		3.5
		3
		2

Safari on iOS	Opera Mini	Android Browser	Blackberry Browser	Opera Mobile	Android Chrome	Android Firefox	IE Mobile	Android UC Browser	Samsung Internet	QQ Browser	Baidu Browser	KaiOS Browser
15	all	94	10	64	94 ⁽³⁾	92	11	12.12	15.0	10.4	7.12	2.5
14.5-14.8		4.4.3-4.4.4	7	12.1			10		14.0
14.0-14.4		4.4		12					13.0
13.4-13.7		4.2-4.3		11.5					12.0
Show all
13.3		4.1		11.1					11.1-11.2
13.2		4		11					10.1
13.0-13.1		3		10					9.2
12.2-12.5 ⁽⁵⁾		2.3							8.2
12.0-12.1 ⁽⁵⁾		2.2							7.2-7.4
11.3-11.4		2.1							6.2-6.4
11.0-11.2									5.0-5.4
10.3									4
10.0-10.2
9.3
9.0-9.2
8.1-8.4
8
7.0-7.1
6.0-6.1
5.0-5.1
4.2-4.3
4.0-4.1
3.2

Notes

This feature is backwards compatible. Browsers not supporting this feature will simply use the cookie as a regular cookie. There is no need to deliver different cookies to clients.

Not shipped with the inital release but later with the 2018 June security update (Patch Tuesday) to Windows 10 RS3 (2017 Fall Creators Update) and newer. More info.
Partial support because only supported in IE 11 on Windows 10 RS3 (2017 Fall Creators Update) and newer, but not in IE 11 on other Windows versions (Windows 7, ...)
Cookies without SameSite are treated as Lax by default, SameSite=None cookies without Secure are rejected.
Partial due to the lack of support in macOS before 10.14 Mojave.
Partial due to the bug that treats SameSite=None and invalid values as Strict in macOS before 10.15 Catalina and in iOS before 13.

Bugs

On Safari in macOS before 10.14.4 and iOS before 12.2, some authentication flows with a cross-site identity provider might fail when SameSite=Lax is used. See the explanation and a workaround.
On Safari before 12.1.1 and iOS before 12.3, manually visiting a redirection link to a cross-site omits Lax cookies from the cross-site request. See the bug.

Resources

Data by caniuse.com
Licensed under the Creative Commons Attribution License v4.0.
https://caniuse.com/same-site-cookie-attribute